WO2021002106A1 - Photodetection element, photodetection element production method, image sensor, dispersion solution, and semiconductor film - Google Patents

Photodetection element, photodetection element production method, image sensor, dispersion solution, and semiconductor film Download PDF

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WO2021002106A1
WO2021002106A1 PCT/JP2020/019571 JP2020019571W WO2021002106A1 WO 2021002106 A1 WO2021002106 A1 WO 2021002106A1 JP 2020019571 W JP2020019571 W JP 2020019571W WO 2021002106 A1 WO2021002106 A1 WO 2021002106A1
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ligand
pbs quantum
mol
atom
group
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真宏 高田
雅司 小野
峻輔 北島
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富士フイルム株式会社
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Publication of WO2021002106A1 publication Critical patent/WO2021002106A1/en
Priority to US17/555,528 priority patent/US20220115611A1/en
Priority to JP2023111270A priority patent/JP2023145474A/en

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Definitions

  • the present invention relates to a photodetector having a photoelectric conversion layer containing PbS quantum dots, a method for manufacturing the photodetector, and an image sensor.
  • the present invention also relates to a dispersion liquid containing PbS quantum dots and a semiconductor film.
  • silicon photodiode using a silicon wafer as a material for a photoelectric conversion layer has been used for a photodetector used in an image sensor or the like.
  • silicon photodiodes have low sensitivity in the infrared region with a wavelength of 900 nm or more.
  • InGaAs-based semiconductor materials known as near-infrared light receiving elements require extremely high-cost processes, such as needing epitaxial growth in order to achieve high quantum efficiency. , Not widespread.
  • Patent Document 1 describes an invention relating to a photodetector using PbS quantum dots as a photoactive layer.
  • the photodetector having a photoelectric conversion layer formed by using semiconductor quantum dots has room for further improvement in the external quantum efficiency (EQE) of photoelectric conversion and the durability against repeated driving. It turned out.
  • EQE external quantum efficiency
  • the present invention provides the following.
  • the PbS quantum dot is a photodetector containing 1.75 mol or more and 1.95 mol or less of Pb atom with respect to 1 mol of S atom.
  • ⁇ 3> The light according to ⁇ 1> or ⁇ 2>, wherein the ligand contains at least one selected from a ligand containing a halogen atom and a polydentate ligand containing two or more coordination portions. Detection element.
  • ⁇ 4> The photodetector according to ⁇ 3>, wherein the ligand containing the halogen atom is an inorganic halide.
  • ⁇ 5> The photodetector according to ⁇ 4>, wherein the inorganic halide contains a Zn atom.
  • ⁇ 6> The photodetector according to any one of ⁇ 3> to ⁇ 5>, wherein the ligand containing a halogen atom contains an iodine atom.
  • ⁇ 7> The above-mentioned one of ⁇ 1> to ⁇ 6>, wherein the ligand contains at least one selected from 3-mercaptopropionic acid, zinc iodide, zinc bromide and indium iodide.
  • ⁇ 8> The photodetector according to any one of ⁇ 1> to ⁇ 7>, wherein the ligand contains two or more kinds of ligands.
  • ⁇ 9> The light according to any one of ⁇ 1> to ⁇ 8>, wherein the ligand contains a ligand containing a halogen atom and a polydentate ligand containing two or more coordination portions. Detection element.
  • the above-mentioned dispersion liquid containing a PbS quantum dot containing 1.75 mol or more and 1.95 mol or less of a Pb atom with respect to 1 mol of an S atom, a ligand coordinating to the PbS quantum dot, and a solvent was used.
  • a method for manufacturing a photodetector which comprises a step of forming a film of an aggregate of PbS quantum dots.
  • ⁇ 12> An image sensor including the photodetection element according to any one of ⁇ 1> to ⁇ 10>.
  • the image sensor according to ⁇ 12> which senses light having a wavelength of 900 to 1600 nm.
  • the image sensor according to ⁇ 12> which is an infrared image sensor.
  • ⁇ 15> A dispersion containing a PbS quantum dot containing 1.75 mol or more and 1.95 mol or less of a Pb atom with respect to 1 mol of an S atom, a ligand coordinating the PbS quantum dot, and a solvent.
  • the PbS quantum dot is a semiconductor film containing 1.75 mol or more and 1.95 mol or less with respect to 1 mol of S atom.
  • the present invention it is possible to provide a photodetector having high external quantum efficiency and excellent durability against repeated driving, a method for manufacturing the photodetector, and an image sensor. Further, it is possible to provide a dispersion liquid and a semiconductor film used for a photodetector or the like having high external quantum efficiency and excellent durability against repeated driving.
  • the contents of the present invention will be described in detail below.
  • "-" is used to mean that the numerical values described before and after it are included as the lower limit value and the upper limit value.
  • the notation that does not describe substitution and non-substituent also includes a group having a substituent (atomic group) as well as a group having no substituent (atomic group).
  • the "alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).
  • the photodetector of the present invention A photodetector having a photoelectric conversion layer containing an aggregate of PbS quantum dots and a ligand coordinating the PbS quantum dots.
  • the PbS quantum dot is characterized by containing 1.75 mol or more and 1.95 mol or less of Pb atom with respect to 1 mol of S atom.
  • the photodetector of the present invention has high external quantum efficiency and excellent durability against repeated driving.
  • the detailed reason for obtaining such an effect is unknown, but it is presumed to be due to the following. That is, since these PbS quantum dots contain 1.75 mol or more and 1.95 mol or less of Pb atoms with respect to 1 mol of S atoms, it is presumed that many Pb atoms are present on the surface of the PbS quantum dots. Therefore, the ligand is easily adsorbed on the surface of the PbS quantum dot, and it is presumed that the ligand coverage on the surface of the PbS quantum dot is high.
  • the PbS quantum dot contains 1.75 mol or more and 1.95 mol or less of Pb atom, preferably 1.75 mol or more and 1.90 or less, and 1.80 or more and 1.90 or less for 1 mol of S atom. Is more preferable. When the content of Pb atoms is 1.95 mol or less with respect to 1 mol of S atoms, a low dark current can be easily obtained.
  • the molar ratio of S atoms to Pb atoms of PbS quantum dots can be calculated by quantifying Pb atoms and S atoms in PbS quantum dots by inductively coupled plasma (ICP) emission spectroscopy.
  • ICP inductively coupled plasma
  • the PbS quantum dots When evaluating the Pb / S ratio of PbS quantum dots containing Pb atoms or S atoms in the ligand, the PbS quantum dots are immersed in a large excess of methanol to remove the ligand from the PbS quantum dots. After that, Pb atoms and S atoms in the PbS quantum dots are quantified and calculated by ICP emission spectroscopic analysis. The removal of the ligand from the PbS quantum dots can be confirmed by the fact that the Pb / S ratio of the PbS quantum dots does not change when the immersion time in methanol is changed.
  • the aggregate of PbS quantum dots refers to a form in which a large number of PbS quantum dots (for example, 100 or more per 1 ⁇ m 2 squares) are arranged close to each other.
  • the PbS quantum dots used in the present invention are composed of PbS particles.
  • the band gap of the PbS quantum dots is preferably 0.5 to 2.0 eV. If the band gap of the PbS quantum dots is within the above range, it can be a photodetector capable of detecting light of various wavelengths depending on the application. For example, it can be a photodetector capable of detecting light in the infrared region.
  • the upper limit of the band gap of the PbS quantum dots is preferably 1.9 eV or less, more preferably 1.8 eV or less, and even more preferably 1.5 eV or less.
  • the lower limit of the band gap of the PbS quantum dots is preferably 0.6 eV or more, and more preferably 0.7 eV or more.
  • the average particle size of PbS quantum dots is preferably 2 nm to 15 nm.
  • the average particle size of the PbS quantum dots refers to the average particle size of 10 PbS quantum dots.
  • a transmission electron microscope may be used for measuring the particle size of the PbS quantum dots.
  • PbS quantum dots include particles of various sizes from several nm to several tens of nm.
  • PbS quantum dots when the average particle size of PbS quantum dots is reduced to a size equal to or smaller than the bore radius of the internal electrons, a phenomenon occurs in which the band gap of PbS quantum dots changes due to the quantum size effect.
  • the average particle size of the PbS quantum dots is 15 nm or less, it is easy to control the band gap by the quantum size effect.
  • the photoelectric conversion layer of the photodetector contains a ligand that coordinates the PbS quantum dots.
  • the ligand include a ligand containing a halogen atom and a polydentate ligand containing two or more coordination portions.
  • the photoelectric conversion layer may contain only one type of ligand, or may contain two or more types of ligands. Among them, the photoelectric conversion layer preferably contains one or more types of a ligand containing a halogen atom and a polydentate ligand.
  • the polydentate ligand When a polydentate ligand is used, the polydentate ligand is easy to chelate to the PbS quantum dot, and the peeling of the ligand from the PbS quantum dot can be suppressed more effectively, resulting in excellent durability. Is obtained. Furthermore, by chelate coordination, steric hindrance between PbS quantum dots can be suppressed, high electrical conductivity can be easily obtained, and high external quantum efficiency can be obtained. When a ligand containing a halogen atom and a polydentate ligand are used in combination, a higher external quantum efficiency can be easily obtained. As mentioned above, the polydentate ligand is presumed to be chelate-coordinated to the PbS quantum dots.
  • the ligand that coordinates the PbS quantum dot when the ligand containing the halogen atom is further contained, the ligand containing the halogen atom is placed in the gap where the polydentate ligand is not coordinated. It is presumed to be coordinated, and it is presumed that the surface defects of PbS quantum dots can be further reduced. Therefore, it is presumed that the external quantum efficiency of the photodetector can be further improved.
  • a ligand containing a halogen atom will be described.
  • the halogen atom contained in the ligand containing the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and the iodine atom is preferable from the viewpoint of coordinating power.
  • the halogen-containing ligand may be an organic halide or an inorganic halide.
  • an inorganic halide is preferable because it is easy to coordinate with both the cation site and the anion site of the PbS quantum dot.
  • the inorganic halide is preferably a compound containing a metal atom selected from a Zn atom, an In atom and a Cd atom, and preferably a compound containing a Zn atom.
  • the inorganic halide is preferably a salt of a metal atom and a halogen atom because it is easily ionized and easily coordinated with PbS quantum dots.
  • halogen-containing ligand examples include zinc iodide, zinc bromide, zinc chloride, indium iodide, indium bromide, indium chloride, cadmium iodide, cadmium bromide, cadmium chloride, and the like.
  • Zinc chloride is particularly preferred.
  • the halogen ion may be dissociated from the ligand containing halogen and the halogen ion may be coordinated on the surface of the PbS quantum dot. Further, the portion of the ligand containing halogen other than halogen may also be coordinated on the surface of the PbS quantum dot.
  • zinc iodide zinc iodide may be coordinated on the surface of PbS quantum dots, and iodine ions and zinc ions are coordinated on the surface of PbS quantum dots. Sometimes it is.
  • the polydentate ligand will be described.
  • the coordination portion contained in the polydentate ligand include a thiol group, an amino group, a hydroxy group, a carboxy group, a sulfo group, a phospho group, and a phosphonic acid group.
  • the polydentate ligand is preferably a compound containing a thiol group because it is easy to coordinate firmly to the surface of the PbS quantum dot (preferably the Pb atom of the PbS quantum dot).
  • polydentate ligand examples include ligands represented by any of the formulas (A) to (C).
  • X A1 and X A2 independently represent a thiol group, an amino group, a hydroxy group, a carboxy group, a sulfo group, a phospho group or a phosphonic acid group.
  • LA1 represents a hydrocarbon group.
  • X B1 and X B2 independently represent a thiol group, an amino group, a hydroxy group, a carboxy group, a sulfo group, a phospho group or a phosphonic acid group.
  • X B3 represents S, O or NH LB1 and LB2 each independently represent a hydrocarbon group.
  • X C1 to X C3 independently represent a thiol group, an amino group, a hydroxy group, a carboxy group, a sulfo group, a phospho group or a phosphonic acid group.
  • X C4 represents N LC1 to LC3 independently represent hydrocarbon groups.
  • the amino groups represented by X A1 , X A2 , X B1 , X B2 , X C1 , X C2 and X C3 are not limited to -NH 2 , but also include substituted amino groups and cyclic amino groups.
  • the substituted amino group include a monoalkylamino group, a dialkylamino group, a monoarylamino group, a diarylamino group, an alkylarylamino group and the like.
  • -NH 2 a monoalkylamino group and a dialkylamino group are preferable, and -NH 2 is more preferable.
  • the L A1, L B1, L B2 , L C1, hydrocarbon group L C2 and L C3 represents preferably an aliphatic hydrocarbon group.
  • the aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group.
  • the hydrocarbon group preferably has 1 to 20 carbon atoms. The upper limit of the number of carbon atoms is preferably 10 or less, more preferably 6 or less, and even more preferably 3 or less.
  • Specific examples of the hydrocarbon group include an alkylene group, an alkenylene group, and an alkynylene group.
  • Examples of the alkylene group include a linear alkylene group, a branched alkylene group and a cyclic alkylene group, and a linear alkylene group or a branched alkylene group is preferable, and a linear alkylene group is more preferable.
  • Examples of the alkenylene group include a linear alkenylene group, a branched alkenylene group and a cyclic alkenylene group, and a linear alkenylene group or a branched alkenylene group is preferable, and a linear alkenylene group is more preferable.
  • alkynylene group examples include a linear alkynylene group and a branched alkynylene group, and a linear alkynylene group is preferable.
  • the alkylene group, alkenylene group and alkynylene group may further have a substituent.
  • the substituent is preferably a group having 1 or more and 10 or less atoms.
  • Preferred specific examples of the group having 1 to 10 atoms are an alkyl group having 1 to 3 carbon atoms [methyl group, ethyl group, propyl group and isopropyl group], an alkenyl group having 2 to 3 carbon atoms [ethenyl group and Propenyl group], alkynyl group having 2 to 4 carbon atoms [ethynyl group, propynyl group, etc.], cyclopropyl group, alkoxy group having 1 to 2 carbon atoms [methoxy group and ethoxy group], acyl group having 2 to 3 carbon atoms [ Acetyl group and propionyl group], alkoxycarbonyl group with 2-3 carbon atoms [methoxycarbonyl group and ethoxycarbonyl group], acyloxy group with 2 carbon atoms [acetyloxy group], acylamino group with 2 carbon atoms [acetylamino group] , Hydroxyalkyl groups with 1 to 3 carbon
  • the X A1 and X A2 is L A1, it is preferable that the separated 1 to 10 atoms, more preferably that are separated 1-6 atoms, that are separated 1-4 atoms Is even more preferable, and it is even more preferable that they are separated by 1 to 3 atoms, and particularly preferably that they are separated by 1 or 2 atoms.
  • the X B1 and X B3 is L B1, it is preferable that the separated 1 to 10 atoms, more preferably that are separated 1-6 atoms, that are separated 1-4 atoms Is even more preferable, and it is even more preferably separated by 1 to 3 atoms, and particularly preferably separated by 1 or 2 atoms.
  • X B2 and X B3 are preferably separated by LB2 by 1 to 10 atoms, more preferably 1 to 6 atoms, and further preferably 1 to 4 atoms. It is even more preferred that they are separated by 1 to 3 atoms, and particularly preferably that they are separated by 1 or 2 atoms.
  • the X C1 and X C4 is L C1, it is preferable that the separated 1 to 10 atoms, more preferably that are separated 1-6 atoms, that are separated 1-4 atoms Is even more preferable, and it is even more preferably separated by 1 to 3 atoms, and particularly preferably separated by 1 or 2 atoms. Further, the X C2 and X C4 is L C2, it is preferable that the separated 1 to 10 atoms, more preferably that are separated 1-6 atoms, more preferably that are separated 1-4 atoms, It is even more preferred that they are separated by 1 to 3 atoms, and particularly preferably that they are separated by 1 or 2 atoms.
  • the X C3 and X C4 is L C3, it is preferable that the separated 1 to 10 atoms, more preferably that are separated 1-6 atoms, more preferably that are separated 1-4 atoms, It is even more preferred that they are separated by 1 to 3 atoms, and particularly preferably that they are separated by 1 or 2 atoms.
  • the X A1 and X A2 is L A1, 1-10 atom are separated
  • the number of atoms constituting the molecular chain of the shortest distance connecting the X A1 and X A2 is 1-10 in It means that there is.
  • X A1 and X A2 are separated by 2 atoms
  • X A1 and X A2 are separated by 3 atoms.
  • the numbers added to the following structural formulas represent the order of the arrangement of atoms constituting the shortest distance molecular chain connecting X A1 and X A2 .
  • the 3-mercaptopropionic acid, at a site corresponding to the X A1 is a carboxy group
  • at the site corresponding to the X A2 is a thiol group
  • a portion corresponding to the L A1 is an ethylene group structure (Compound having the following structure).
  • X A1 (carboxy group) and X A2 (thiol group) are separated by 2 atoms by LA1 (ethylene group).
  • X B1 and X B3 is L B1, that are separated 1-10 atoms, by X B2 and X B3 is L B2, that are separated 1-10 atoms, by X C1 and X C4 is L C1, that are separated 1-10 atoms, by X C2 and X C4 is L C2, that are separated 1-10 atoms, by X C3 and X C4 is L C3, of that separated 1-10 atoms
  • the meaning is the same as above.
  • polydentate ligands include 3-mercaptopropionic acid, thioglycolic acid, 2-aminoethanol, 2-aminoethanediol, 2-mercaptoethanol, glycolic acid, ethylene glycol, ethylenediamine, aminosulfonic acid, and glycine.
  • a compound having a complex stability constant K1 between the polydentate ligand and the Pb atom of the PbS quantum dot of 6 or more is preferably used.
  • the complex stability constant K1 of the polydentate ligand is more preferably 8 or more, and further preferably 10 or more.
  • the strength of the bond between the PbS quantum dot and the polydentate ligand can be increased.
  • the complex stability constant K1 is a constant determined by the relationship between the ligand and the metal atom to be coordinated, and is represented by the following formula (b).
  • a plurality of ligands may be coordinated to one metal atom, but in the present invention, it is represented by the formula (b) when one ligand molecule is coordinated to one metal atom.
  • the complex stability constant K1 is defined as an index of the strength of coordination bonds.
  • the complex stability constant K1 between the ligand and the metal atom can be obtained by spectroscopy, magnetic resonance spectroscopy, potentiometry, solubility measurement, chromatography, calorimetry, freezing point measurement, vapor pressure measurement, relaxation measurement, and viscosity. There are measurement, surface tension measurement, etc.
  • Sc-Database ver. which summarizes the results from various methods and research institutes.
  • the complex stability constant K1 was determined by using 5.85 (Academi Software) (2010).
  • the complex stability constant K1 is Sc-Database ver. If it is not in 5.85, A. E. Martell and R.M. M. The values described in Critical Stability Constants by Smith are used.
  • the photoelectric conversion layer containing an aggregate of PbS quantum dots and a ligand coordinating to the PbS quantum dots is a PbS quantum dot containing 1.75 mol or more and 1.95 mol or less of Pb atom with respect to 1 mol of S atom.
  • a step of applying a dispersion liquid containing a ligand coordinating to the PbS quantum dots and a solvent on the substrate to form a film of the aggregates of the PbS quantum dots (PbS quantum dot aggregate forming step). It is preferable to form through.
  • a PbS quantum dot containing 1.75 mol or more and 1.95 mol or less of a Pb atom with respect to 1 mol of S atom and a ligand coordinating to the PbS quantum dot It is preferable to include a step of forming a film of an aggregate of PbS quantum dots using a dispersion liquid containing, and a solvent.
  • the method of applying the dispersion liquid on the substrate is not particularly limited. Examples thereof include a spin coating method, a dip method, an inkjet method, a dispenser method, a screen printing method, a letterpress printing method, an intaglio printing method, and a spray coating method.
  • a ligand exchange step may be further performed to exchange the ligand coordinated with the PbS quantum dots with another ligand.
  • a ligand solution containing the ligand A and the solvent is applied to the membrane of the PbS quantum dot aggregate formed by the PbS quantum dot aggregate forming step, and the PbS quantum dot is added.
  • the ligand coordinated with is exchanged for the ligand A.
  • the ligand A may contain two or more kinds of ligands, and two kinds of ligand solutions may be used in combination. Examples of the ligand A include the above-mentioned ligand containing a halogen atom and a polydentate ligand containing two or more coordination portions.
  • a desired ligand may be imparted to the surface of the PbS quantum dots in advance, and this dispersion liquid may be applied onto the substrate to form a photoelectric conversion layer.
  • the content of PbS quantum dots in the dispersion is preferably 1 to 500 mg / mL, more preferably 10 to 200 mg / mL, and even more preferably 20 to 100 mg / mL.
  • Examples of the solvent contained in the dispersion liquid and the ligand solution include ester-based solvents, ketone-based solvents, alcohol-based solvents, amide-based solvents, ether-based solvents, and hydrocarbon-based solvents.
  • ester-based solvents include ester-based solvents, ketone-based solvents, alcohol-based solvents, amide-based solvents, ether-based solvents, and hydrocarbon-based solvents.
  • paragraph number 0223 of WO 2015/166779 can be referred to, the contents of which are incorporated herein by reference.
  • an ester solvent substituted with a cyclic alkyl group and a ketone solvent substituted with a cyclic alkyl group can also be used. It is preferable that the amount of metal impurities in the solvent is small, and the metal content is, for example, 10 mass ppb (parts per parts) or less.
  • a solvent at the mass ppt (parts per parts) level may be used, and such a solvent is provided by, for example, Toyo Synthetic Co., Ltd. (The Chemical Daily, November 13, 2015).
  • Examples of the method for removing impurities such as metals from the solvent include distillation (molecular distillation, thin film distillation, etc.) and filtration using a filter.
  • the filter pore diameter of the filter used for filtration is preferably 10 ⁇ m or less, more preferably 5 ⁇ m or less, and even more preferably 3 ⁇ m or less.
  • the filter material is preferably polytetrafluoroethylene, polyethylene or nylon.
  • the solvent may contain isomers (compounds having the same number of atoms but different structures). Further, only one kind of isomer may be contained, or a plurality of kinds may be contained.
  • the thickness of the photoelectric conversion layer of the photodetector is preferably 10 to 600 nm, more preferably 50 to 600 nm, further preferably 100 to 600 nm, and even more preferably 150 to 600 nm. ..
  • the upper limit of the thickness is preferably 550 nm or less, more preferably 500 nm or less, and even more preferably 450 nm or less.
  • the refractive index of the photoelectric conversion layer with respect to light of the target wavelength detected by the photodetector is preferably 2.0 to 3.0, more preferably 2.1 to 2.8, and 2.2 to 2.8. It is more preferably 2.7. According to this aspect, when the photodetector is configured as a photodiode, it becomes easy to realize a high light absorption rate, that is, a high external quantum efficiency.
  • the photodetection element of the present invention is preferably an infrared light detection element.
  • the target light to be detected by the above-mentioned photodetector is preferably light having a wavelength in the infrared region.
  • the light having a wavelength in the infrared region is preferably light having a wavelength exceeding 700 nm, more preferably light having a wavelength of 800 nm or more, and further preferably light having a wavelength of 900 nm or more.
  • the light having a wavelength in the infrared region is preferably light having a wavelength of 2000 nm or less, and more preferably light having a wavelength of 1600 nm or less.
  • the light detection element of the present invention may simultaneously detect light having a wavelength in the infrared region and light having a wavelength in the visible region (preferably light having a wavelength in the range of 400 to 700 nm).
  • Examples of the type of photodetector include a photoconductor type photodetector and a photodiode type photodetector. Of these, a photodiode-type photodetector is preferable because a high signal-to-noise ratio (SN ratio) can be easily obtained.
  • SN ratio signal-to-noise ratio
  • FIG. 1 shows an embodiment of a photodiode-type photodetector.
  • the arrows in the figure represent the incident light on the photodetector.
  • the photodetection element 1 shown in FIG. 1 includes a lower electrode 12, an upper electrode 11 facing the lower electrode 12, and a photoelectric conversion layer 13 provided between the lower electrode 12 and the upper electrode 11.
  • the photodetection element 1 shown in FIG. 1 is used by injecting light from above the upper electrode 11.
  • the photoelectric conversion layer 13 is the photoelectric conversion layer according to the present invention described above.
  • the preferred embodiment of the photoelectric conversion layer is as described above.
  • the optical path length L ⁇ satisfies the relationship of the following equation (1-1), and more preferably the relationship of the following equation (1-2) is satisfied.
  • the wavelength ⁇ and the optical path length L ⁇ satisfy such a relationship, the light (incident light) incident from the upper electrode 11 side is reflected by the surface of the lower electrode 12 in the photoelectric conversion layer 13. It is possible to align the phase with the light (reflected light), and as a result, the light is strengthened by the optical interference effect, and higher external quantum efficiency can be obtained.
  • ⁇ is the wavelength of the target light to be detected by the photodetector.
  • L ⁇ is the optical path length of light having a wavelength ⁇ from the surface 12a on the photoelectric conversion layer 13 side of the lower electrode 12 to the surface 13a on the upper electrode layer side of the photoelectric conversion layer 13.
  • m is an integer greater than or equal to 0.
  • M is preferably an integer of 0 to 4, more preferably an integer of 0 to 3, and even more preferably an integer of 0 to 2. According to this aspect, the transport characteristics of charges such as holes and electrons are good, and the external quantum efficiency of the photodetection device can be further enhanced.
  • the optical path length means the product of the physical thickness of the substance through which light is transmitted and the refractive index.
  • the photoelectric conversion layer 13 when the thickness of the photoelectric conversion layer is d 1 and the refractive index of the photoelectric conversion layer with respect to the wavelength ⁇ 1 is N 1 , the wavelength ⁇ 1 transmitted through the photoelectric conversion layer 13 The optical path length of light is N 1 ⁇ d 1 .
  • the photoelectric conversion layer 13 is composed of two or more laminated films, or when an intermediate layer described later is present between the photoelectric conversion layer 13 and the lower electrode 12, the integrated value of the optical path length of each layer is calculated.
  • the optical path length L ⁇ when the photoelectric conversion layer 13 is composed of two or more laminated films, or when an intermediate layer described later is present between the photoelectric conversion layer 13 and the lower electrode 12, the integrated value of the optical path length of each layer is calculated.
  • the optical path length L ⁇ when the photoelectric conversion layer 13 is composed of two or more laminated films, or when an intermediate layer described later is present between the photoelectric
  • the upper electrode 11 is preferably a transparent electrode formed of a conductive material that is substantially transparent to the wavelength of the target light detected by the photodetector.
  • substantially transparent means that the transmittance is 50% or more, preferably 60% or more, and particularly preferably 80% or more.
  • the material of the upper electrode 11 include a conductive metal oxide. Specific examples include tin oxide, zinc oxide, indium oxide, indium tungsten oxide, indium zinc oxide (IZO), indium tin oxide (ITO), and fluorine-doped tin oxide (fluorine-topped). Tin oxide: FTO) and the like.
  • the film thickness of the upper electrode 11 is not particularly limited, and is preferably 0.01 to 100 ⁇ m, more preferably 0.01 to 10 ⁇ m, and particularly preferably 0.01 to 1 ⁇ m.
  • the thickness of each layer can be measured by observing the cross section of the light detection element 1 using a scanning electron microscope (SEM) or the like.
  • Examples of the material forming the lower electrode 12 include metals such as platinum, gold, nickel, copper, silver, indium, ruthenium, palladium, rhodium, iridium, osnium, and aluminum, the above-mentioned conductive metal oxides, carbon materials, and the like. Examples include conductive polymers.
  • the carbon material may be any material having conductivity, and examples thereof include fullerenes, carbon nanotubes, graphite, graphene and the like.
  • the lower electrode 12 a thin film of metal or a conductive metal oxide (including a thin film formed by vapor deposition), or a glass substrate or a plastic substrate having this thin film is preferable.
  • a glass substrate or the plastic substrate glass having a thin film of gold or platinum or glass on which platinum is vapor-deposited is preferable.
  • the film thickness of the lower electrode 12 is not particularly limited, and is preferably 0.01 to 100 ⁇ m, more preferably 0.01 to 10 ⁇ m, and particularly preferably 0.01 to 1 ⁇ m.
  • a transparent substrate may be arranged on the surface of the upper electrode 11 on the light incident side (the surface opposite to the photoelectric conversion layer 13 side).
  • Examples of the type of transparent substrate include a glass substrate, a resin substrate, and a ceramic substrate.
  • an intermediate layer may be provided between the photoelectric conversion layer 13 and the lower electrode 12 and / or between the photoelectric conversion layer 13 and the upper electrode 11.
  • the intermediate layer include a blocking layer, an electron transport layer, and a hole transport layer.
  • a preferred embodiment includes a mode in which the hole transport layer is provided between the photoelectric conversion layer 13 and the lower electrode 12 and between the photoelectric conversion layer 13 and the upper electrode 11. It is possible that one of the photoelectric conversion layer 13 and the lower electrode 12 and one of the photoelectric conversion layer 13 and the upper electrode 11 has an electron transport layer and the other has a hole transport layer. preferable.
  • the hole transport layer and the electron transport layer may be a single-layer film or a laminated film having two or more layers.
  • the blocking layer is a layer having a function of preventing reverse current.
  • the blocking layer is also called a short circuit prevention layer.
  • Examples of the material forming the blocking layer include silicon oxide, magnesium oxide, aluminum oxide, calcium carbonate, cesium carbonate, polyvinyl alcohol, polyurethane, titanium oxide, tin oxide, zinc oxide, niobium oxide, tungsten oxide and the like.
  • the blocking layer may be a single-layer film or a laminated film having two or more layers.
  • the electron transport layer is a layer having a function of transporting electrons generated in the photoelectric conversion layer 13 to the upper electrode 11 or the lower electrode 12.
  • the electron transport layer is also called a hole block layer.
  • the electron transport layer is formed of an electron transport material capable of exerting this function. Examples of the electron transporting material include fullerene compounds such as [6,6] -Phenyl-C61-Butyric Acid Metyl Ester (PC 61 BM), perylene compounds such as perylene tetracarboxydiimide, tetracyanoquinodimethane, titanium oxide, and tin oxide.
  • the electron transport layer may be a single-layer film or a laminated film having two or more layers.
  • the hole transport layer is a layer having a function of transporting holes generated in the photoelectric conversion layer 13 to the upper electrode 11 or the lower electrode 12.
  • the hole transport layer is also called an electron block layer.
  • the hole transport layer is formed of a hole transport material capable of exerting this function.
  • the organic hole transport material or the like described in paragraph Nos. 0209 to 0212 of JP-A-2001-291534 can also be used.
  • semiconductor quantum dots can also be used as the hole transport material.
  • Examples of the semiconductor quantum dot material constituting the semiconductor quantum dot include general semiconductor crystals [a) group IV semiconductors, b) group IV-IV, group III-V, or group II-VI compound semiconductors, c) II.
  • Specific examples thereof include semiconductor materials having a relatively narrow bandgap, such as PbS, PbSe, InN, InAs, Ge, InAs, InGaAs, CuInS, CuInSe, CuInGaSe, InSb, Si, and InP.
  • a ligand may be coordinated on the surface of the semiconductor quantum dot. Examples of the ligand include the polydentate ligand described above.
  • the image sensor of the present invention includes the above-mentioned photodetector of the present invention.
  • the configuration of the image sensor is not particularly limited as long as it includes the photodetector of the present invention and functions as an image sensor.
  • the image sensor of the present invention may include an infrared transmission filter layer.
  • the infrared transmission filter layer preferably has low light transmittance in the visible wavelength band, and more preferably has an average transmittance of light in the wavelength range of 400 to 650 nm of 10% or less. It is more preferably 5.5% or less, and particularly preferably 5% or less.
  • Examples of the infrared transmission filter layer include those composed of a resin film containing a coloring material.
  • Examples of the coloring material include chromatic color materials such as red color material, green color material, blue color material, yellow color material, purple color material, and orange color material, and black color material.
  • the color material contained in the infrared transmission filter layer is preferably a combination of two or more kinds of chromatic color materials to form black, or preferably contains a black color material.
  • Examples of the combination of chromatic color materials in the case of forming black by combining two or more kinds of chromatic color materials include the following aspects (C1) to (C7).
  • (C1) An embodiment containing a red color material and a blue color material.
  • C2 An embodiment containing a red color material, a blue color material, and a yellow color material.
  • C3 An embodiment containing a red color material, a blue color material, a yellow color material, and a purple color material.
  • C4 An embodiment containing a red color material, a blue color material, a yellow color material, a purple color material, and a green color material.
  • C5 An embodiment containing a red color material, a blue color material, a yellow color material, and a green color material.
  • C6 An embodiment containing a red color material, a blue color material, and a green color material.
  • C7 An embodiment containing a yellow color material and a purple color material.
  • the chromatic color material may be a pigment or a dye. Pigments and dyes may be included.
  • the black color material is preferably an organic black color material.
  • examples of the organic black color material include a bisbenzofuranone compound, an azomethine compound, a perylene compound, and an azo compound.
  • the infrared transmission filter layer may further contain an infrared absorber.
  • infrared absorbers include pyrolopyrrole compounds, cyanine compounds, squarylium compounds, phthalocyanine compounds, naphthalocyanine compounds, quaterylene compounds, merocyanine compounds, croconium compounds, oxonor compounds, iminium compounds, dithiol compounds, triarylmethane compounds, pyromethene compounds, and azomethine compounds.
  • examples thereof include compounds, anthraquinone compounds, dibenzofuranone compounds, dithiolene metal complexes, metal oxides, and metal boroides.
  • the spectral characteristics of the infrared transmission filter layer can be appropriately selected according to the application of the image sensor.
  • a filter layer satisfying any of the following spectral characteristics (1) to (5) can be mentioned.
  • the maximum value of the light transmittance in the film thickness direction in the wavelength range of 400 to 830 nm is 20% or less (preferably 15% or less, more preferably 10% or less), and the light in the film thickness direction.
  • the maximum value of the light transmittance in the film thickness direction in the wavelength range of 400 to 950 nm is 20% or less (preferably 15% or less, more preferably 10% or less), and the light in the film thickness direction.
  • the maximum value of the light transmittance in the film thickness direction in the wavelength range of 400 to 1100 nm is 20% or less (preferably 15% or less, more preferably 10% or less), and the wavelength range is 1400 to 1500 nm.
  • a filter layer having a minimum value of 70% or more preferably 75% or more, more preferably 80% or more.
  • the maximum value of the light transmittance in the film thickness direction in the wavelength range of 400 to 1300 nm is 20% or less (preferably 15% or less, more preferably 10% or less), and the wavelength range is 1600 to 2000 nm.
  • a filter layer having a minimum value of 70% or more preferably 75% or more, more preferably 80% or more).
  • infrared transmission filters Japanese Patent Application Laid-Open No. 2013-077009, Japanese Patent Application Laid-Open No. 2014-130173, Japanese Patent Application Laid-Open No. 2014-130338, International Publication No. 2015/166779, International Publication No. 2016/178346, International Publication No.
  • the films described in 2016/190162, International Publication No. 2018/016232, JP-A-2016-177079, JP-A-2014-130332, and International Publication No. 2016/0277798 can be used.
  • the infrared transmission filter may be used in combination of two or more filters, or a dual bandpass filter that transmits a specific two or more wavelength regions with one filter may be used.
  • the image sensor of the present invention may include an infrared shielding filter for the purpose of improving various performances such as noise reduction.
  • the infrared shielding filter include, for example, International Publication No. 2016/186050, International Publication No. 2016/035695, Japanese Patent No. 6248945, International Publication No. 2019/021767, Japanese Patent Application Laid-Open No. 2017-06793, Patent. Examples thereof include the filters described in Japanese Patent Application Laid-Open No. 6506529.
  • the image sensor of the present invention may include a dielectric multilayer film.
  • the dielectric multilayer film include those in which a plurality of layers of a dielectric thin film having a high refractive index (high refractive index material layer) and a dielectric thin film having a low refractive index (low refractive index material layer) are alternately laminated.
  • the number of laminated dielectric thin films in the dielectric multilayer film is not particularly limited, but is preferably 2 to 100 layers, more preferably 4 to 60 layers, and even more preferably 6 to 40 layers.
  • As the material used for forming the high refractive index material layer a material having a refractive index of 1.7 to 2.5 is preferable.
  • Specific examples include Sb 2 O 3 , Sb 2 S 3 , Bi 2 O 3 , CeO 2 , CeF 3 , HfO 2 , La 2 O 3 , Nd 2 O 3 , Pr 6 O 11 , Sc 2 O 3 , SiO. , Ta 2 O 5 , TiO 2 , TlCl, Y 2 O 3 , ZnSe, ZnS, ZrO 2, and the like.
  • a material having a refractive index of 1.2 to 1.6 is preferable.
  • the method for forming the dielectric multilayer film is not particularly limited, and for example, an ion plating method, a vacuum deposition method such as an ion beam, a physical vapor deposition method (PVD method) such as sputtering, or a chemical vapor deposition method. (CVD method) and the like.
  • each of the high refractive index material layer and the low refractive index material layer is preferably 0.1 ⁇ to 0.5 ⁇ when the wavelength of the light to be blocked is ⁇ (nm).
  • Specific examples of the dielectric multilayer film include the dielectric multilayer films described in JP-A-2014-130344 and JP-A-2018-010296.
  • the dielectric multilayer film preferably has a transmission wavelength band in the infrared region (preferably a wavelength region having a wavelength of more than 700 nm, more preferably a wavelength region having a wavelength of more than 800 nm, and further preferably a wavelength region having a wavelength of more than 900 nm).
  • the maximum transmittance in the transmission wavelength band is preferably 70% or more, more preferably 80% or more, and further preferably 90% or more.
  • the maximum transmittance in the light-shielding wavelength band is preferably 20% or less, more preferably 10% or less, and further preferably 5% or less.
  • the average transmittance in the transmission wavelength band is preferably 60% or more, more preferably 70% or more, and further preferably 80% or more.
  • the wavelength range of the transmission wavelength band, when the center wavelength lambda t1 wavelengths showing a maximum transmittance is preferably the central wavelength lambda t1 ⁇ 100 nm, more preferably the central wavelength lambda t1 ⁇ 75 nm, It is more preferable that the center wavelength is ⁇ t1 ⁇ 50 nm.
  • the dielectric multilayer film may have only one transmission wavelength band (preferably, a transmission wavelength band having a maximum transmittance of 90% or more), or may have a plurality of transmission wavelength bands.
  • the image sensor of the present invention may include a color separation filter layer.
  • the color separation filter layer include a filter layer including colored pixels.
  • Examples of the types of colored pixels include red pixels, green pixels, blue pixels, yellow pixels, cyan pixels, magenta pixels, and the like.
  • the color separation filter layer may include two or more colored pixels, or may have only one color. It can be appropriately selected according to the application and purpose.
  • the color separation filter layer for example, the filter described in International Publication No. 2019/039172 can be used.
  • the colored pixels of each color may be adjacent to each other, and a partition wall may be provided between the colored pixels.
  • the material of the partition wall is not particularly limited. Examples thereof include organic materials such as siloxane resin and fluororesin, and inorganic particles such as silica particles.
  • the partition wall may be made of a metal such as tungsten or aluminum.
  • the image sensor of the present invention includes an infrared transmission filter layer and a color separation layer
  • the color separation layer is provided on an optical path different from the infrared transmission filter layer. It is also preferable that the infrared transmission filter layer and the color separation layer are arranged two-dimensionally. The fact that the infrared transmission filter layer and the color separation layer are arranged two-dimensionally means that at least a part of both is present on the same plane.
  • the image sensor of the present invention may include an intermediate layer such as a flattening layer, a base layer, and an adhesion layer, an antireflection film, and a lens.
  • an antireflection film for example, a film prepared from the composition described in International Publication No. 2019/017280 can be used.
  • the lens for example, the structure described in International Publication No. 2018/092600 can be used.
  • the photodetector of the present invention also has excellent sensitivity to light having a wavelength in the infrared region. Therefore, the image sensor of the present invention can be preferably used as an infrared image sensor. Further, the image sensor of the present invention can be preferably used for sensing light having a wavelength of 900 to 2000 nm, and more preferably for sensing light having a length of 900 to 1600 nm.
  • the dispersion liquid of the present invention contains a PbS quantum dot containing 1.75 mol or more and 1.95 mol or less of a Pb atom with respect to 1 mol of an S atom, a ligand coordinating the PbS quantum dot, and a solvent. ..
  • the PbS quantum dots used in the dispersion are synonymous with the PbS quantum dots described in the section on photodetectors.
  • the content of PbS quantum dots in the dispersion is preferably 1 to 500 mg / mL, more preferably 10 to 200 mg / mL, and even more preferably 20 to 100 mg / mL.
  • Examples of the solvent used in the dispersion liquid include those described as the solvent contained in the dispersion liquid and the ligand solution described above.
  • the content of the solvent in the dispersion is preferably 50 to 99% by mass, more preferably 70 to 99% by mass, and further preferably 90 to 98% by mass with respect to the total mass of the dispersion. preferable.
  • the ligand contained in the dispersion liquid acts as a ligand for coordinating PbS quantum dots and has a molecular structure that easily causes steric hindrance, and serves as a dispersant for dispersing PbS quantum dots in a solvent. It is preferable that it also fulfills.
  • the ligand is preferably a ligand having at least 6 or more carbon atoms in the main chain, and is a ligand having 10 or more carbon atoms in the main chain. More preferably.
  • the ligand may be either a saturated compound or an unsaturated compound.
  • the ligand examples include decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, erucic acid, oleylamine, dodecylamine, dodecanethiol, 1,2-hexadecanethiol, and trioctyl. Examples thereof include phosphine oxide and cetrimonium bromide.
  • the ligand is preferably one that does not easily remain in the film after the formation of the semiconductor film. Specifically, it is preferable that the molecular weight is small.
  • the ligands are preferably oleic acid and oleylamine from the viewpoint that the PbS quantum dots have dispersion stability and are unlikely to remain on the semiconductor film.
  • the ligand contained in the dispersion liquid may be a ligand containing a halogen atom described in the section of the photodetector, a multidentate ligand containing two or more coordination portions, or the like.
  • the content of the ligand in the dispersion is preferably 0.1 mmol / L to 200 mmol / L, more preferably 0.5 mmol / L to 10 mmol / L, based on the total volume of the dispersion. ..
  • the semiconductor film of the present invention is a semiconductor film containing an aggregate of PbS quantum dots and a ligand that coordinates the PbS quantum dots, and the PbS quantum dots have Pb atoms for 1 mol of S atoms.
  • the PbS quantum dot preferably contains 1.75 mol or more and 1.90 mol or less of Pb atom with respect to 1 mol of S atom.
  • the PbS quantum dot has the same meaning as the PbS quantum dot described in the section of the photodetector.
  • Examples of the ligand that coordinates the PbS quantum dot include a ligand containing a halogen atom described in the section of the photodetector, and a polydentate ligand containing two or more coordination portions, which are preferable examples. Is the same.
  • the semiconductor film of the present invention is preferably used for a photoelectric conversion layer of a photodetection element or the like.
  • Example 1 1.28 mL of oleic acid, 2 mmol of lead oxide and 38 mL of octadecene were measured in a flask and heated at 110 ° C. under vacuum for 90 minutes to obtain a precursor solution. The temperature of the solution was then adjusted to 95 ° C., the system was placed in a nitrogen flow state, and then 1 mmol of hexamethyldisiratene was injected with 5 mL of octadecene. Immediately after the injection, the flask was naturally cooled, and when the temperature reached 30 ° C., 12 mL of hexane was added and the solution was recovered.
  • a photodiode-type photodetector was manufactured by the following method.
  • a titanium oxide film was formed by 50 nm sputtering on a quartz glass substrate with a fluorine-doped tin oxide film.
  • the dispersion liquid of PbS quantum dots was dropped onto the titanium oxide film formed on the substrate and spin-coated at 2500 rpm to form a PbS quantum dot aggregate film (step 1).
  • a methanol solution of 3-mercaptopropionic acid (concentration 0.1 mol / L) was added dropwise onto the PbS quantum dot aggregate film as a ligand solution, and the mixture was allowed to stand for 1 minute and spin-dried at 2500 rpm. went.
  • step 2 methanol was dropped onto the PbS quantum dot aggregate membrane and spin-dried at 2500 rpm for 20 seconds to disperse the ligand coordinated to the PbS quantum dots from oleic acid to 3-mercaptopropionic acid.
  • the position was exchanged (step 2).
  • step 1 and step 2 as one cycle was repeated for 30 cycles, and the photoelectric conversion layer, which is a PbS quantum dot aggregate film in which the ligand was exchanged from oleic acid to 3-mercaptopropionic acid, was formed at 100 nm. Formed by thickness.
  • molybdenum oxide was formed on the photoelectric conversion layer with a thickness of 50 nm and gold was formed by continuous vapor deposition to obtain a photodiode-type photodetector.
  • Example 2 A dispersion of PbS quantum dots was obtained in the same manner as in Example 1 except that hexamethyldisirateian was changed to 2.0 mmol.
  • the bandgap of the PbS quantum dots was approximately 1.32 eV.
  • the Pb / S ratio (molar ratio) of the PbS quantum dots was 1.81.
  • Example 3 A precursor solution was obtained by measuring 6.74 mL of oleic acid, 6.3 mmol of lead oxide and 30 mL of octadecene in a flask and heating at 120 ° C. under vacuum for 100 minutes. The temperature of the solution was then adjusted to 100 ° C., the system was placed in a nitrogen flow state, and then 2.6 mmol of hexamethyldisiratene was injected with 5 mL of octadecene. After holding for 1 minute after injection, the flask was naturally cooled, 40 mL of toluene was added when the temperature reached 30 ° C., and the solution was recovered.
  • Example 4 Same as Example 1 except that a methanol solution of zinc iodide (concentration 0.025 mol / L) was used instead of a methanol solution of 3-mercaptopropionic acid (concentration 0.1 mol / L) as the ligand solution.
  • a light detection element was manufactured by the above method.
  • Example 5 Same as Example 1 except that a methanol solution of zinc bromide (concentration 0.025 mol / L) was used instead of the methanol solution of 3-mercaptopropionic acid (concentration 0.1 mol / L) as the ligand solution.
  • a light detection element was manufactured by the above method.
  • Example 6 Same as Example 1 except that a methanol solution of indium iodide (concentration 0.025 mol / L) was used instead of the methanol solution of 3-mercaptopropionic acid (concentration 0.1 mol / L) as the ligand solution.
  • a light detection element was manufactured by the above method.
  • Example 7 Example 1 except that a methanol solution containing 3-mercaptopropionic acid and zinc iodide (3-mercaptopropionic acid concentration 0.01 mol / L, zinc iodide concentration 0.025 mol / L) was used as the ligand solution.
  • a photodetector was produced in the same manner as in.
  • Example 4 except that the PbS quantum dots having a Pb / S ratio (molar ratio) of 1.90 were changed to the PbS quantum dots having a Pb / S ratio (molar ratio) of 1.75 described in Example 3.
  • a photodetector was produced in the same manner as in 7 to 7.
  • Example 1 As the dispersion liquid of PbS quantum dots, a commercially available dispersion liquid of PbS quantum dots (manufactured by Sigma-Aldrich, product number 900735) was used. The bandgap estimated from the absorption measurement of the dispersion of PbS quantum dots was about 1.32 eV. Further, when the Pb / S ratio (molar ratio) of the PbS quantum dots was calculated by the above method, the Pb / S ratio (molar ratio) of the PbS quantum dots was 1.6. Using this dispersion of PbS quantum dots, a photodetector was produced in the same manner as in Example 1.
  • the degree of change in the external quantum efficiency after repeating the calculation of the external quantum efficiency 50 times (the value of the external quantum efficiency measured at the first time ⁇ the value of the external quantum efficiency measured at the 50th time) is calculated and repeated.
  • the durability against driving was evaluated. The smaller the value of the degree of change in the external quantum efficiency, the better the durability against repeated driving.
  • the photodetector of the example had higher external quantum efficiency than the comparative example, the value of the degree of change of the external quantum efficiency was small, and the durability against repeated driving was excellent.
  • an image sensor was prepared by a known method together with an optical filter prepared according to the methods described in International Publication No. 2016/186050 and International Publication No. 2016/190162, and solidified. By incorporating it into an image sensor, an image sensor having good visible and infrared imaging performance can be obtained.
  • Photodetection element 11 Upper electrode 12: Lower electrode 13: Photoelectric conversion layer

Abstract

Provided are a photodetection element having high external quantum efficiency and having excellent durability with respect to being repeatedly driven, a photodetection element production method, and an image sensor. Also provided are a dispersion solution and a semiconductor film. This photodetection element comprises an ensemble of PbS quantum dots and a ligand coordinated to the PbS quantum dots, and the PbS quantum dots contain 1.75-1.95 moles of Pb atoms relative to 1 mole of S atoms.

Description

光検出素子、光検出素子の製造方法、イメージセンサ、分散液および半導体膜Photodetectors, methods of manufacturing photodetectors, image sensors, dispersions and semiconductor films
　本発明は、ＰｂＳ量子ドットを含む光電変換層を有する光検出素子、光検出素子の製造方法、および、イメージセンサに関する。また、本発明は、ＰｂＳ量子ドットを含む分散液および半導体膜に関する。 The present invention relates to a photodetector having a photoelectric conversion layer containing PbS quantum dots, a method for manufacturing the photodetector, and an image sensor. The present invention also relates to a dispersion liquid containing PbS quantum dots and a semiconductor film.
　近年、スマートフォンや監視カメラ、車載カメラ等の領域において、赤外域の光を検出可能な光検出素子に注目が集まっている。 In recent years, attention has been focused on photodetectors capable of detecting infrared light in areas such as smartphones, surveillance cameras, and in-vehicle cameras.
　従来より、イメージセンサなどに用いられる光検出素子には、光電変換層の素材としてシリコンウエハを用いたシリコンフォトダイオードが使用されている。しかしながら、シリコンフォトダイオードでは、波長９００ｎｍ以上の赤外域では感度が低い。 Conventionally, a silicon photodiode using a silicon wafer as a material for a photoelectric conversion layer has been used for a photodetector used in an image sensor or the like. However, silicon photodiodes have low sensitivity in the infrared region with a wavelength of 900 nm or more.
　また、近赤外光の受光素子として知られるＩｎＧａＡｓ系の半導体材料は、高い量子効率を実現するためにはエピタキシャル成長が必要であるなど、非常に高コストなプロセスを必要としていることが課題であり、普及が進んでいない。 Another problem is that InGaAs-based semiconductor materials known as near-infrared light receiving elements require extremely high-cost processes, such as needing epitaxial growth in order to achieve high quantum efficiency. , Not widespread.
　また、近年では、半導体量子ドットについての研究が進められている。例えば、特許文献１には、ＰｂＳ量子ドットを光活性層に用いた光検出器に関する発明が記載されている。 In recent years, research on semiconductor quantum dots has been underway. For example, Patent Document 1 describes an invention relating to a photodetector using PbS quantum dots as a photoactive layer.
特表２０１６－５３２３０１号公報Special Table 2016-532301 Gazette
　本発明者の検討によれば、半導体量子ドットを用いて形成した光電変換層を有する光検出素子は、光電変換の外部量子効率（ＥＱＥ）や、繰り返し駆動に対する耐久性についてさらなる改善の余地があることが分かった。 According to the study of the present inventor, the photodetector having a photoelectric conversion layer formed by using semiconductor quantum dots has room for further improvement in the external quantum efficiency (EQE) of photoelectric conversion and the durability against repeated driving. It turned out.
　よって、本発明の目的は、外部量子効率が高く、繰り返し駆動に対する耐久性に優れた光検出素子、光検出素子の製造方法およびイメージセンサを提供することにある。また、本発明の目的は、外部量子効率が高く、繰り返し駆動に対する耐久性に優れた光検出素子などに用いられる分散液および半導体膜を提供することにある。 Therefore, an object of the present invention is to provide a photodetection element having high external quantum efficiency and excellent durability against repeated driving, a method for manufacturing the photodetection element, and an image sensor. Another object of the present invention is to provide a dispersion liquid and a semiconductor film used for a photodetector or the like having high external quantum efficiency and excellent durability against repeated driving.
　本発明者の検討によれば、以下の構成とすることにより上記目的を達成できることを見出し、本発明を完成するに至った。よって、本発明は以下を提供する。
＜１＞　ＰｂＳ量子ドットの集合体と、上記ＰｂＳ量子ドットに配位する配位子と、を含む光電変換層を有する光検出素子であって、
　上記ＰｂＳ量子ドットは、Ｓ原子１モルに対してＰｂ原子を１．７５モル以上１．９５モル以下含む、光検出素子。
＜２＞　上記ＰｂＳ量子ドットは、Ｓ原子１モルに対してＰｂ原子を１．７５モル以上１．９０モル以下含む、＜１＞に記載の光検出素子。
＜３＞　上記配位子は、ハロゲン原子を含む配位子、および、配位部を２以上含む多座配位子から選ばれる少なくとも１種を含む＜１＞または＜２＞に記載の光検出素子。
＜４＞　上記ハロゲン原子を含む配位子が無機ハロゲン化物である、＜３＞に記載の光検出素子。
＜５＞　上記無機ハロゲン化物はＺｎ原子を含む、＜４＞に記載の光検出素子。
＜６＞　上記ハロゲン原子を含む配位子がヨウ素原子を含む、＜３＞～＜５＞のいずれか１つに記載の光検出素子。
＜７＞　上記配位子が、３－メルカプトプロピオン酸、ヨウ化亜鉛、臭化亜鉛およびヨウ化インジウムから選ばれる少なくとも１種を含む、＜１＞～＜６＞のいずれか１つに記載の光検出素子。
＜８＞　上記配位子は、２種以上の配位子を含む、＜１＞～＜７＞のいずれか１つに記載の光検出素子。
＜９＞　上記配位子は、ハロゲン原子を含む配位子と、配位部を２以上含む多座配位子とを含む、＜１＞～＜８＞のいずれか１つに記載の光検出素子。
＜１０＞　フォトダイオード型の光検出素子である、＜１＞～＜９＞のいずれか１つに記載の光検出素子。
＜１１＞　＜１＞～＜１０＞のいずれか１つに記載の光検出素子の製造方法であって、
　Ｓ原子１モルに対してＰｂ原子を１．７５モル以上１．９５モル以下含むＰｂＳ量子ドットと、上記ＰｂＳ量子ドットに配位する配位子と、溶剤と、を含む分散液を用いて上記ＰｂＳ量子ドットの集合体の膜を形成する工程を含む、光検出素子の製造方法。
＜１２＞　＜１＞～＜１０＞のいずれか１つに記載の光検出素子を含むイメージセンサ。＜１３＞　波長９００～１６００ｎｍの光をセンシングする、＜１２＞に記載のイメージセンサ。
＜１４＞　赤外線イメージセンサである、＜１２＞に記載のイメージセンサ。
＜１５＞　Ｓ原子１モルに対してＰｂ原子を１．７５モル以上１．９５モル以下含むＰｂＳ量子ドットと、上記ＰｂＳ量子ドットに配位する配位子と、溶剤と、を含む分散液。
＜１６＞　ＰｂＳ量子ドットの集合体と、上記ＰｂＳ量子ドットに配位する配位子と、を含む半導体膜であって、
　上記ＰｂＳ量子ドットは、Ｓ原子１モルに対して１．７５モル以上１．９５モル以下含む、半導体膜。 According to the study of the present inventor, it has been found that the above object can be achieved by adopting the following configuration, and the present invention has been completed. Therefore, the present invention provides the following.
<1> A photodetector having a photoelectric conversion layer containing an aggregate of PbS quantum dots and a ligand coordinating the PbS quantum dots.
The PbS quantum dot is a photodetector containing 1.75 mol or more and 1.95 mol or less of Pb atom with respect to 1 mol of S atom.
<2> The photodetector according to <1>, wherein the PbS quantum dot contains 1.75 mol or more and 1.90 mol or less of Pb atom with respect to 1 mol of S atom.
<3> The light according to <1> or <2>, wherein the ligand contains at least one selected from a ligand containing a halogen atom and a polydentate ligand containing two or more coordination portions. Detection element.
<4> The photodetector according to <3>, wherein the ligand containing the halogen atom is an inorganic halide.
<5> The photodetector according to <4>, wherein the inorganic halide contains a Zn atom.
<6> The photodetector according to any one of <3> to <5>, wherein the ligand containing a halogen atom contains an iodine atom.
<7> The above-mentioned one of <1> to <6>, wherein the ligand contains at least one selected from 3-mercaptopropionic acid, zinc iodide, zinc bromide and indium iodide. Photodetection element.
<8> The photodetector according to any one of <1> to <7>, wherein the ligand contains two or more kinds of ligands.
<9> The light according to any one of <1> to <8>, wherein the ligand contains a ligand containing a halogen atom and a polydentate ligand containing two or more coordination portions. Detection element.
<10> The photodetection element according to any one of <1> to <9>, which is a photodiode type photodetection element.
<11> The method for manufacturing a photodetection according to any one of <1> to <10>.
The above-mentioned dispersion liquid containing a PbS quantum dot containing 1.75 mol or more and 1.95 mol or less of a Pb atom with respect to 1 mol of an S atom, a ligand coordinating to the PbS quantum dot, and a solvent was used. A method for manufacturing a photodetector, which comprises a step of forming a film of an aggregate of PbS quantum dots.
<12> An image sensor including the photodetection element according to any one of <1> to <10>. <13> The image sensor according to <12>, which senses light having a wavelength of 900 to 1600 nm.
<14> The image sensor according to <12>, which is an infrared image sensor.
<15> A dispersion containing a PbS quantum dot containing 1.75 mol or more and 1.95 mol or less of a Pb atom with respect to 1 mol of an S atom, a ligand coordinating the PbS quantum dot, and a solvent.
<16> A semiconductor film containing an aggregate of PbS quantum dots and a ligand coordinating the PbS quantum dots.
The PbS quantum dot is a semiconductor film containing 1.75 mol or more and 1.95 mol or less with respect to 1 mol of S atom.
　本発明によれば、外部量子効率が高く、繰り返し駆動に対する耐久性に優れた光検出素子、光検出素子の製造方法およびイメージセンサを提供することができる。また、外部量子効率が高く、繰り返し駆動に対する耐久性に優れた光検出素子などに用いられる分散液および半導体膜を提供することができる。 According to the present invention, it is possible to provide a photodetector having high external quantum efficiency and excellent durability against repeated driving, a method for manufacturing the photodetector, and an image sensor. Further, it is possible to provide a dispersion liquid and a semiconductor film used for a photodetector or the like having high external quantum efficiency and excellent durability against repeated driving.
光検出素子の一実施形態を示す図である。It is a figure which shows one Embodiment of a photodetection element.
　以下において、本発明の内容について詳細に説明する。
　本明細書において、「～」とはその前後に記載される数値を下限値および上限値として含む意味で使用される。
　本明細書における基（原子団）の表記において、置換および無置換を記していない表記は、置換基を有さない基（原子団）と共に置換基を有する基（原子団）をも包含する。例えば、「アルキル基」とは、置換基を有さないアルキル基（無置換アルキル基）のみならず、置換基を有するアルキル基（置換アルキル基）をも包含する。 The contents of the present invention will be described in detail below.
In the present specification, "-" is used to mean that the numerical values described before and after it are included as the lower limit value and the upper limit value.
In the notation of a group (atomic group) in the present specification, the notation that does not describe substitution and non-substituent also includes a group having a substituent (atomic group) as well as a group having no substituent (atomic group). For example, the "alkyl group" includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).
＜光検出素子＞
　本発明の光検出素子は、
　ＰｂＳ量子ドットの集合体と、ＰｂＳ量子ドットに配位する配位子と、を含む光電変換層を有する光検出素子であって、
　ＰｂＳ量子ドットは、Ｓ原子１モルに対してＰｂ原子を１．７５モル以上１．９５モル以下含むことを特徴とする。 <Photodetector>
The photodetector of the present invention
A photodetector having a photoelectric conversion layer containing an aggregate of PbS quantum dots and a ligand coordinating the PbS quantum dots.
The PbS quantum dot is characterized by containing 1.75 mol or more and 1.95 mol or less of Pb atom with respect to 1 mol of S atom.
　本発明の光検出素子は、外部量子効率が高く、繰り返し駆動に対する耐久性に優れている。このような効果が得られる詳細な理由は不明であるが次によるものであると推測される。すなわち、このＰｂＳ量子ドットは、Ｓ原子１モルに対してＰｂ原子を１．７５モル以上１．９５モル以下含むので、ＰｂＳ量子ドットの表面にＰｂ原子が多く存在していると推測される。このため、ＰｂＳ量子ドットの表面に配位子が吸着されやすくなり、ＰｂＳ量子ドット表面の配位子被覆率が高いと推測される。ＰｂＳ量子ドット表面の配位子被覆率を高めることができることにより、ＰｂＳ量子ドットの表面にトラップされる電子を減少させることができ、その結果、優れた外部量子効率が得られたと推測される。また、ＰｂＳ量子ドットの表面に配位子が強固に配位し、ＰｂＳ量子ドットの表面から配位子が剥離しにくくできたため、繰り返し駆動に対する優れた耐久性が得られたと推測される。 The photodetector of the present invention has high external quantum efficiency and excellent durability against repeated driving. The detailed reason for obtaining such an effect is unknown, but it is presumed to be due to the following. That is, since these PbS quantum dots contain 1.75 mol or more and 1.95 mol or less of Pb atoms with respect to 1 mol of S atoms, it is presumed that many Pb atoms are present on the surface of the PbS quantum dots. Therefore, the ligand is easily adsorbed on the surface of the PbS quantum dot, and it is presumed that the ligand coverage on the surface of the PbS quantum dot is high. By increasing the ligand coverage on the surface of the PbS quantum dots, it is possible to reduce the number of electrons trapped on the surface of the PbS quantum dots, and as a result, it is presumed that excellent external quantum efficiency was obtained. Further, it is presumed that the ligand was firmly coordinated to the surface of the PbS quantum dot and the ligand was hard to be separated from the surface of the PbS quantum dot, so that excellent durability against repeated driving was obtained.
　ＰｂＳ量子ドットは、Ｓ原子１モルに対してＰｂ原子を１．７５モル以上１．９５モル以下含み、１．７５モル以上１．９０以下含むことが好ましく、１．８０以上１．９０以下含むことがより好ましい。Ｐｂ原子の含有量がＳ原子１モルに対して１．９５モル以下であれば、低暗電流が得られやすい。ＰｂＳ量子ドットのＳ原子とＰｂ原子とのモル比は、誘導結合プラズマ（ＩＣＰ）発光分光分析にてＰｂＳ量子ドット中のＰｂ原子およびＳ原子をそれぞれ定量して算出することができる。なお、配位子にＰｂ原子またはＳ原子を含むＰｂＳ量子ドットのＰｂ／Ｓ比を評価する際には、ＰｂＳ量子ドットを大過剰のメタノール中に浸漬してＰｂＳ量子ドットから配位子を除去した後、ＩＣＰ発光分光分析にてＰｂＳ量子ドット中のＰｂ原子およびＳ原子をそれぞれ定量して算出する。ＰｂＳ量子ドットから配位子が除去されたことについては、メタノールへの浸漬時間を変えた際に、ＰｂＳ量子ドットのＰｂ／Ｓ比が変化しないことで確認することができる。 The PbS quantum dot contains 1.75 mol or more and 1.95 mol or less of Pb atom, preferably 1.75 mol or more and 1.90 or less, and 1.80 or more and 1.90 or less for 1 mol of S atom. Is more preferable. When the content of Pb atoms is 1.95 mol or less with respect to 1 mol of S atoms, a low dark current can be easily obtained. The molar ratio of S atoms to Pb atoms of PbS quantum dots can be calculated by quantifying Pb atoms and S atoms in PbS quantum dots by inductively coupled plasma (ICP) emission spectroscopy. When evaluating the Pb / S ratio of PbS quantum dots containing Pb atoms or S atoms in the ligand, the PbS quantum dots are immersed in a large excess of methanol to remove the ligand from the PbS quantum dots. After that, Pb atoms and S atoms in the PbS quantum dots are quantified and calculated by ICP emission spectroscopic analysis. The removal of the ligand from the PbS quantum dots can be confirmed by the fact that the Pb / S ratio of the PbS quantum dots does not change when the immersion time in methanol is changed.
　なお、本明細書において、ＰｂＳ量子ドットの集合体とは、多数（例えば、１μｍ２四方当たり１００個以上）のＰｂＳ量子ドットが互いに近接して配置された形態をいう。 In the present specification, the aggregate of PbS quantum dots refers to a form in which a large number of PbS quantum dots (for example, 100 or more per 1 μm 2 squares) are arranged close to each other.
　本発明で用いられるＰｂＳ量子ドットは、ＰｂＳ粒子で構成されている。 The PbS quantum dots used in the present invention are composed of PbS particles.
　ＰｂＳ量子ドットのバンドギャップは、０．５～２．０ｅＶであることが好ましい。ＰｂＳ量子ドットのバンドギャップが上記範囲であれば、用途に応じて様々な波長の光を検出可能な光検出素子とすることができる。例えば、赤外域の光を検出可能な光検出素子とすることができる。ＰｂＳ量子ドットのバンドギャップの上限は１．９ｅＶ以下であることが好ましく、１．８ｅＶ以下であることがより好ましく、１．５ｅＶ以下であることが更に好ましい。ＰｂＳ量子ドットのバンドギャップの下限は０．６ｅＶ以上であることが好ましく、０．７ｅＶ以上であることが更に好ましい。 The band gap of the PbS quantum dots is preferably 0.5 to 2.0 eV. If the band gap of the PbS quantum dots is within the above range, it can be a photodetector capable of detecting light of various wavelengths depending on the application. For example, it can be a photodetector capable of detecting light in the infrared region. The upper limit of the band gap of the PbS quantum dots is preferably 1.9 eV or less, more preferably 1.8 eV or less, and even more preferably 1.5 eV or less. The lower limit of the band gap of the PbS quantum dots is preferably 0.6 eV or more, and more preferably 0.7 eV or more.
　ＰｂＳ量子ドットの平均粒径は、２ｎｍ～１５ｎｍであることが好ましい。なお、ＰｂＳ量子ドットの平均粒径は、ＰｂＳ量子ドット１０個の平均粒径をいう。ＰｂＳ量子ドットの粒径の測定には、透過型電子顕微鏡を用いればよい。 The average particle size of PbS quantum dots is preferably 2 nm to 15 nm. The average particle size of the PbS quantum dots refers to the average particle size of 10 PbS quantum dots. A transmission electron microscope may be used for measuring the particle size of the PbS quantum dots.
　一般的にＰｂＳ量子ドットは、数ｎｍ～数十ｎｍまでの様々な大きさの粒子を含む。ＰｂＳ量子ドットでは内在する電子のボーア半径以下の大きさまでＰｂＳ量子ドットの平均粒径を小さくすると、量子サイズ効果によりＰｂＳ量子ドットのバンドギャップが変化する現象が生じる。ＰｂＳ量子ドットの平均粒径が、１５ｎｍ以下であれば、量子サイズ効果によるバンドギャップの制御を行いやすい。 Generally, PbS quantum dots include particles of various sizes from several nm to several tens of nm. In PbS quantum dots, when the average particle size of PbS quantum dots is reduced to a size equal to or smaller than the bore radius of the internal electrons, a phenomenon occurs in which the band gap of PbS quantum dots changes due to the quantum size effect. When the average particle size of the PbS quantum dots is 15 nm or less, it is easy to control the band gap by the quantum size effect.
　光検出素子の光電変換層は、ＰｂＳ量子ドットに配位する配位子を含んでいる。配位子としては、ハロゲン原子を含む配位子、および、配位部を２以上含む多座配位子が挙げられる。光電変換層は、配位子を１種のみ含んでいてもよく、２種以上含んでいてもよい。なかでも、光電変換層は、ハロゲン原子を含む配位子と多座配位子とをそれぞれ１種以上ずつ含むことが好ましい。
　ハロゲン原子を含む配位子を用いた場合は、ＰｂＳ量子ドットの配位子による表面被覆率を高めやすく、その結果より高い外部量子効率などが得られる。
　多座配位子を用いた場合は、多座配位子がＰｂＳ量子ドットにキレート配位しやすく、ＰｂＳ量子ドットからの配位子の剥がれなどをより効果的に抑制でき、優れた耐久性が得られる。更には、キレート配位することでＰｂＳ量子ドット同士の立体障害を抑制でき、高い電気伝導性が得られやすくなり、高い外部量子効率が得られる。
　そして、ハロゲン原子を含む配位子と多座配位子とを併用した場合は、より高い外部量子効率が得られやすい。上述したように、多座配位子はＰｂＳ量子ドットに対してキレート配位すると推測される。そして、ＰｂＳ量子ドットに配位する配位子として、更に、ハロゲン原子を含む配位子を含む場合には、多座配位子が配位していない隙間にハロゲン原子を含む配位子が配位すると推測され、ＰｂＳ量子ドットの表面欠陥をより低減することができると推測される。このため、光検出素子の外部量子効率をより向上させることができると推測される。 The photoelectric conversion layer of the photodetector contains a ligand that coordinates the PbS quantum dots. Examples of the ligand include a ligand containing a halogen atom and a polydentate ligand containing two or more coordination portions. The photoelectric conversion layer may contain only one type of ligand, or may contain two or more types of ligands. Among them, the photoelectric conversion layer preferably contains one or more types of a ligand containing a halogen atom and a polydentate ligand.
When a ligand containing a halogen atom is used, it is easy to increase the surface coverage of the PbS quantum dot with the ligand, and as a result, higher external quantum efficiency can be obtained.
When a polydentate ligand is used, the polydentate ligand is easy to chelate to the PbS quantum dot, and the peeling of the ligand from the PbS quantum dot can be suppressed more effectively, resulting in excellent durability. Is obtained. Furthermore, by chelate coordination, steric hindrance between PbS quantum dots can be suppressed, high electrical conductivity can be easily obtained, and high external quantum efficiency can be obtained.
When a ligand containing a halogen atom and a polydentate ligand are used in combination, a higher external quantum efficiency can be easily obtained. As mentioned above, the polydentate ligand is presumed to be chelate-coordinated to the PbS quantum dots. Then, as the ligand that coordinates the PbS quantum dot, when the ligand containing the halogen atom is further contained, the ligand containing the halogen atom is placed in the gap where the polydentate ligand is not coordinated. It is presumed to be coordinated, and it is presumed that the surface defects of PbS quantum dots can be further reduced. Therefore, it is presumed that the external quantum efficiency of the photodetector can be further improved.
　まず、ハロゲン原子を含む配位子について説明する。ハロゲン原子を含む配位子に含まれるハロゲン原子としては、フッ素原子、塩素原子、臭素原子およびヨウ素原子が挙げられ、配位力の観点からヨウ素原子であることが好ましい。 First, a ligand containing a halogen atom will be described. Examples of the halogen atom contained in the ligand containing the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and the iodine atom is preferable from the viewpoint of coordinating power.
　ハロゲンを含む配位子は、有機ハロゲン化物であってもよく、無機ハロゲン化物であってもよい。なかでも、ＰｂＳ量子ドットの陽イオンサイト及び陰イオンサイトの両方に配位しやすいという理由から無機ハロゲン化物であることが好ましい。また、無機ハロゲン化物は、Ｚｎ原子、Ｉｎ原子およびＣｄ原子から選ばれる金属原子を含む化合物であることが好ましく、Ｚｎ原子を含む化合物であることが好ましい。無機ハロゲン化物としては、容易にイオン化して、ＰｂＳ量子ドットに配位しやすいという理由から金属原子とハロゲン原子との塩であることが好ましい。 The halogen-containing ligand may be an organic halide or an inorganic halide. Of these, an inorganic halide is preferable because it is easy to coordinate with both the cation site and the anion site of the PbS quantum dot. Further, the inorganic halide is preferably a compound containing a metal atom selected from a Zn atom, an In atom and a Cd atom, and preferably a compound containing a Zn atom. The inorganic halide is preferably a salt of a metal atom and a halogen atom because it is easily ionized and easily coordinated with PbS quantum dots.
　ハロゲンを含む配位子の具体例としては、ヨウ化亜鉛、臭化亜鉛、塩化亜鉛、ヨウ化インジウム、臭化インジウム、塩化インジウム、ヨウ化カドミウム、臭化カドミウム、塩化カドミウムなどが挙げられ、ヨウ化亜鉛が特に好ましい。 Specific examples of the halogen-containing ligand include zinc iodide, zinc bromide, zinc chloride, indium iodide, indium bromide, indium chloride, cadmium iodide, cadmium bromide, cadmium chloride, and the like. Zinc chloride is particularly preferred.
　なお、ハロゲンを含む配位子では、ハロゲンを含む配位子からハロゲンイオンが解離してＰｂＳ量子ドットの表面にハロゲンイオンが配位していることもある。また、ハロゲンを含む配位子のハロゲン以外の部位についても、ＰｂＳ量子ドットの表面に配位している場合もある。具体例を挙げて説明すると、ヨウ化亜鉛の場合は、ヨウ化亜鉛がＰｂＳ量子ドットの表面に配位していることもあれば、ヨウ素イオンや亜鉛イオンがＰｂＳ量子ドットの表面に配位していることもある。 In the ligand containing halogen, the halogen ion may be dissociated from the ligand containing halogen and the halogen ion may be coordinated on the surface of the PbS quantum dot. Further, the portion of the ligand containing halogen other than halogen may also be coordinated on the surface of the PbS quantum dot. To explain with a specific example, in the case of zinc iodide, zinc iodide may be coordinated on the surface of PbS quantum dots, and iodine ions and zinc ions are coordinated on the surface of PbS quantum dots. Sometimes it is.
　次に、多座配位子について説明する。多座配位子に含まれる配位部としては、チオール基、アミノ基、ヒドロキシ基、カルボキシ基、スルホ基、ホスホ基、ホスホン酸基が挙げられる。ＰｂＳ量子ドットの表面（好ましくはＰｂＳ量子ドットのＰｂ原子）に強固に配位しやすいという理由から、多座配位子はチオール基を含む化合物であることが好ましい。 Next, the polydentate ligand will be described. Examples of the coordination portion contained in the polydentate ligand include a thiol group, an amino group, a hydroxy group, a carboxy group, a sulfo group, a phospho group, and a phosphonic acid group. The polydentate ligand is preferably a compound containing a thiol group because it is easy to coordinate firmly to the surface of the PbS quantum dot (preferably the Pb atom of the PbS quantum dot).
　多座配位子としては、式（Ａ）～（Ｃ）のいずれかで表される配位子が挙げられる。
Figure JPOXMLDOC01-appb-C000001
 Examples of the polydentate ligand include ligands represented by any of the formulas (A) to (C).
Figure JPOXMLDOC01-appb-C000001
　式（Ａ）中、ＸＡ１及びＸＡ２はそれぞれ独立して、チオール基、アミノ基、ヒドロキシ基、カルボキシ基、スルホ基、ホスホ基又はホスホン酸基を表し、
　ＬＡ１は炭化水素基を表す。 In formula (A), X A1 and X A2 independently represent a thiol group, an amino group, a hydroxy group, a carboxy group, a sulfo group, a phospho group or a phosphonic acid group.
LA1 represents a hydrocarbon group.
　式（Ｂ）中、ＸＢ１及びＸＢ２はそれぞれ独立して、チオール基、アミノ基、ヒドロキシ基、カルボキシ基、スルホ基、ホスホ基又はホスホン酸基を表し、
　ＸＢ３は、Ｓ、Ｏ又はＮＨを表し、
　ＬＢ１及びＬＢ２は、それぞれ独立して炭化水素基を表す。 In formula (B), X B1 and X B2 independently represent a thiol group, an amino group, a hydroxy group, a carboxy group, a sulfo group, a phospho group or a phosphonic acid group.
X B3 represents S, O or NH
LB1 and LB2 each independently represent a hydrocarbon group.
　式（Ｃ）中、ＸＣ１～ＸＣ３はそれぞれ独立して、チオール基、アミノ基、ヒドロキシ基、カルボキシ基、スルホ基、ホスホ基又はホスホン酸基を表し、
　ＸＣ４は、Ｎを表し、
　ＬＣ１～ＬＣ３は、それぞれ独立して炭化水素基を表す。 In formula (C), X C1 to X C3 independently represent a thiol group, an amino group, a hydroxy group, a carboxy group, a sulfo group, a phospho group or a phosphonic acid group.
X C4 represents N
LC1 to LC3 independently represent hydrocarbon groups.
　ＸＡ１、ＸＡ２、ＸＢ１、ＸＢ２、ＸＣ１、ＸＣ２およびＸＣ３が表すアミノ基には、－ＮＨ２に限定されず、置換アミノ基および環状アミノ基も含まれる。置換アミノ基としては、モノアルキルアミノ基、ジアルキルアミノ基、モノアリールアミノ基、ジアリールアミノ基、アルキルアリールアミノ基などが挙げられる。これらの基が表すアミノ基としては、－ＮＨ２、モノアルキルアミノ基、ジアルキルアミノ基が好ましく、－ＮＨ２であることがより好ましい。 The amino groups represented by X A1 , X A2 , X B1 , X B2 , X C1 , X C2 and X C3 are not limited to -NH 2 , but also include substituted amino groups and cyclic amino groups. Examples of the substituted amino group include a monoalkylamino group, a dialkylamino group, a monoarylamino group, a diarylamino group, an alkylarylamino group and the like. As the amino group represented by these groups, -NH 2 , a monoalkylamino group and a dialkylamino group are preferable, and -NH 2 is more preferable.
　ＬＡ１、ＬＢ１、ＬＢ２、ＬＣ１、ＬＣ２およびＬＣ３が表す炭化水素基としては、脂肪族炭化水素基であることが好ましい。脂肪族炭化水素基は、飽和脂肪族炭化水素基であってもよく、不飽和脂肪族炭化水素基であってもよい。炭化水素基の炭素数は、１～２０が好ましい。炭素数の上限は、１０以下が好ましく、６以下がより好ましく、３以下が更に好ましい。炭化水素基の具体例としては、アルキレン基、アルケニレン基、アルキニレン基が挙げられる。 The L A1, L B1, L B2 , L C1, hydrocarbon group L C2 and L C3 represents preferably an aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group. The hydrocarbon group preferably has 1 to 20 carbon atoms. The upper limit of the number of carbon atoms is preferably 10 or less, more preferably 6 or less, and even more preferably 3 or less. Specific examples of the hydrocarbon group include an alkylene group, an alkenylene group, and an alkynylene group.
　アルキレン基は、直鎖アルキレン基、分岐アルキレン基および環状アルキレン基が挙げられ、直鎖アルキレン基または分岐アルキレン基であることが好ましく、直鎖アルキレン基であることがより好ましい。アルケニレン基は、直鎖アルケニレン基、分岐アルケニレン基および環状アルケニレン基が挙げられ、直鎖アルケニレン基または分岐アルケニレン基であることが好ましく、直鎖アルケニレン基であることがより好ましい。アルキニレン基は、直鎖アルキニレン基および分岐アルキニレン基が挙げられ、直鎖アルキニレン基であることが好ましい。アルキレン基、アルケニレン基およびアルキニレン基はさらに置換基を有していてもよい。置換基は、原子数１以上１０以下の基であることが好ましい。原子数１以上１０以下の基の好ましい具体例としては、炭素数１～３のアルキル基〔メチル基、エチル基、プロピル基、及びイソプロピル基〕、炭素数２～３のアルケニル基〔エテニル基およびプロペニル基〕、炭素数２～４のアルキニル基〔エチニル基、プロピニル基等〕、シクロプロピル基、炭素数１～２のアルコキシ基〔メトキシ基およびエトキシ基〕、炭素数２～３のアシル基〔アセチル基、及びプロピオニル基〕、炭素数２～３のアルコキシカルボニル基〔メトキシカルボニル基およびエトキシカルボニル基〕、炭素数２のアシルオキシ基〔アセチルオキシ基〕、炭素数２のアシルアミノ基〔アセチルアミノ基〕、炭素数１～３のヒドロキシアルキル基〔ヒドロキシメチル基、ヒドロキシエチル基、ヒドロキシプロピル基〕、アルデヒド基、ヒドロキシ基、カルボキシ基、スルホ基、ホスホ基、カルバモイル基、シアノ基、イソシアネート基、チオール基、ニトロ基、ニトロキシ基、イソチオシアネート基、シアネート基、チオシアネート基、アセトキシ基、アセトアミド基、ホルミル基、ホルミルオキシ基、ホルムアミド基、スルファミノ基、スルフィノ基、スルファモイル基、ホスホノ基、アセチル基、ハロゲン原子、アルカリ金属原子等が挙げられる。 Examples of the alkylene group include a linear alkylene group, a branched alkylene group and a cyclic alkylene group, and a linear alkylene group or a branched alkylene group is preferable, and a linear alkylene group is more preferable. Examples of the alkenylene group include a linear alkenylene group, a branched alkenylene group and a cyclic alkenylene group, and a linear alkenylene group or a branched alkenylene group is preferable, and a linear alkenylene group is more preferable. Examples of the alkynylene group include a linear alkynylene group and a branched alkynylene group, and a linear alkynylene group is preferable. The alkylene group, alkenylene group and alkynylene group may further have a substituent. The substituent is preferably a group having 1 or more and 10 or less atoms. Preferred specific examples of the group having 1 to 10 atoms are an alkyl group having 1 to 3 carbon atoms [methyl group, ethyl group, propyl group and isopropyl group], an alkenyl group having 2 to 3 carbon atoms [ethenyl group and Propenyl group], alkynyl group having 2 to 4 carbon atoms [ethynyl group, propynyl group, etc.], cyclopropyl group, alkoxy group having 1 to 2 carbon atoms [methoxy group and ethoxy group], acyl group having 2 to 3 carbon atoms [ Acetyl group and propionyl group], alkoxycarbonyl group with 2-3 carbon atoms [methoxycarbonyl group and ethoxycarbonyl group], acyloxy group with 2 carbon atoms [acetyloxy group], acylamino group with 2 carbon atoms [acetylamino group] , Hydroxyalkyl groups with 1 to 3 carbon atoms [hydroxymethyl group, hydroxyethyl group, hydroxypropyl group], aldehyde group, hydroxy group, carboxy group, sulfo group, phospho group, carbamoyl group, cyano group, isocyanate group, thiol group , Nitro group, nitroxy group, isothiocyanate group, cyanate group, thiocyanate group, acetoxy group, acetamide group, formyl group, formyloxy group, formamide group, sulfamino group, sulfino group, sulfamoyl group, phosphono group, acetyl group, halogen atom , Alkali metal atom and the like.
　式（Ａ）において、ＸＡ１とＸＡ２はＬＡ１によって、１～１０原子隔てられていることが好ましく、１～６原子隔てられていることがより好ましく、１～４原子隔てられていることが更に好ましく、１～３原子隔てられていることがより一層好ましく、１または２原子隔てられていることが特に好ましい。 In formula (A), the X A1 and X A2 is L A1, it is preferable that the separated 1 to 10 atoms, more preferably that are separated 1-6 atoms, that are separated 1-4 atoms Is even more preferable, and it is even more preferable that they are separated by 1 to 3 atoms, and particularly preferably that they are separated by 1 or 2 atoms.
　式（Ｂ）において、ＸＢ１とＸＢ３はＬＢ１によって、１～１０原子隔てられていることが好ましく、１～６原子隔てられていることがより好ましく、１～４原子隔てられていることが更に好ましく、１～３原子隔てられていることがより一層好ましく、１または２原子隔てられていることが特に好ましい。また、ＸＢ２とＸＢ３はＬＢ２によって、１～１０原子隔てられていることが好ましく、１～６原子隔てられていることがより好ましく、１～４原子隔てられていることが更に好ましく、１～３原子隔てられていることがより一層好ましく、１または２原子隔てられていることが特に好ましい。 In the formula (B), the X B1 and X B3 is L B1, it is preferable that the separated 1 to 10 atoms, more preferably that are separated 1-6 atoms, that are separated 1-4 atoms Is even more preferable, and it is even more preferably separated by 1 to 3 atoms, and particularly preferably separated by 1 or 2 atoms. Further, X B2 and X B3 are preferably separated by LB2 by 1 to 10 atoms, more preferably 1 to 6 atoms, and further preferably 1 to 4 atoms. It is even more preferred that they are separated by 1 to 3 atoms, and particularly preferably that they are separated by 1 or 2 atoms.
　式（Ｃ）において、ＸＣ１とＸＣ４はＬＣ１によって、１～１０原子隔てられていることが好ましく、１～６原子隔てられていることがより好ましく、１～４原子隔てられていることが更に好ましく、１～３原子隔てられていることがより一層好ましく、１または２原子隔てられていることが特に好ましい。また、ＸＣ２とＸＣ４はＬＣ２によって、１～１０原子隔てられていることが好ましく、１～６原子隔てられていることがより好ましく、１～４原子隔てられていることが更に好ましく、１～３原子隔てられていることがより一層好ましく、１または２原子隔てられていることが特に好ましい。また、ＸＣ３とＸＣ４はＬＣ３によって、１～１０原子隔てられていることが好ましく、１～６原子隔てられていることがより好ましく、１～４原子隔てられていることが更に好ましく、１～３原子隔てられていることがより一層好ましく、１または２原子隔てられていることが特に好ましい。 In formula (C), the X C1 and X C4 is L C1, it is preferable that the separated 1 to 10 atoms, more preferably that are separated 1-6 atoms, that are separated 1-4 atoms Is even more preferable, and it is even more preferably separated by 1 to 3 atoms, and particularly preferably separated by 1 or 2 atoms. Further, the X C2 and X C4 is L C2, it is preferable that the separated 1 to 10 atoms, more preferably that are separated 1-6 atoms, more preferably that are separated 1-4 atoms, It is even more preferred that they are separated by 1 to 3 atoms, and particularly preferably that they are separated by 1 or 2 atoms. Further, the X C3 and X C4 is L C3, it is preferable that the separated 1 to 10 atoms, more preferably that are separated 1-6 atoms, more preferably that are separated 1-4 atoms, It is even more preferred that they are separated by 1 to 3 atoms, and particularly preferably that they are separated by 1 or 2 atoms.
　なお、「ＸＡ１とＸＡ２はＬＡ１によって、１～１０原子隔てられている」とは、ＸＡ１とＸＡ２とをつなぐ最短距離の分子鎖を構成する原子の数が１～１０個であることを意味する。例えば、下記式（Ａ１）の場合は、ＸＡ１とＸＡ２とが２原子隔てられており、下記式（Ａ２）および式（Ａ３）の場合は、ＸＡ１とＸＡ２とが３原子隔てられている。以下の構造式に付記した数字は、ＸＡ１とＸＡ２とをつなぐ最短距離の分子鎖を構成する原子の配列の順番を表している。
Figure JPOXMLDOC01-appb-C000002
 Incidentally, "the X A1 and X A2 is L A1, 1-10 atom are separated," the number of atoms constituting the molecular chain of the shortest distance connecting the X A1 and X A2 is 1-10 in It means that there is. For example, in the case of the following formula (A1), X A1 and X A2 are separated by 2 atoms, and in the case of the following formulas (A2) and (A3), X A1 and X A2 are separated by 3 atoms. ing. The numbers added to the following structural formulas represent the order of the arrangement of atoms constituting the shortest distance molecular chain connecting X A1 and X A2 .
Figure JPOXMLDOC01-appb-C000002
　具体的化合物を挙げて説明すると、３－メルカプトプロピオン酸は、ＸＡ１に相当する部位がカルボキシ基で、ＸＡ２に相当する部位がチオール基で、ＬＡ１に相当する部位がエチレン基である構造の化合物である（下記構造の化合物）。３－メルカプトプロピオン酸においては、ＸＡ１（カルボキシ基）とＸＡ２（チオール基）とがＬＡ１（エチレン基）によって２原子隔てられている。
Figure JPOXMLDOC01-appb-C000003
 To explain by way of specific compounds, the 3-mercaptopropionic acid, at a site corresponding to the X A1 is a carboxy group, at the site corresponding to the X A2 is a thiol group, a portion corresponding to the L A1 is an ethylene group structure (Compound having the following structure). In 3-mercaptopropionic acid, X A1 (carboxy group) and X A2 (thiol group) are separated by 2 atoms by LA1 (ethylene group).
Figure JPOXMLDOC01-appb-C000003
　ＸＢ１とＸＢ３はＬＢ１によって、１～１０原子隔てられていること、ＸＢ２とＸＢ３はＬＢ２によって、１～１０原子隔てられていること、ＸＣ１とＸＣ４はＬＣ１によって、１～１０原子隔てられていること、ＸＣ２とＸＣ４はＬＣ２によって、１～１０原子隔てられていること、ＸＣ３とＸＣ４はＬＣ３によって、１～１０原子隔てられていることの意味についても上記と同様である。 By X B1 and X B3 is L B1, that are separated 1-10 atoms, by X B2 and X B3 is L B2, that are separated 1-10 atoms, by X C1 and X C4 is L C1, that are separated 1-10 atoms, by X C2 and X C4 is L C2, that are separated 1-10 atoms, by X C3 and X C4 is L C3, of that separated 1-10 atoms The meaning is the same as above.
　多座配位子の具体例としては、３－メルカプトプロピオン酸、チオグリコール酸、２－アミノエタノール、２－アミノエタンジオール、２－メルカプトエタノール、グリコール酸、エチレングリコール、エチレンジアミン、アミノスルホン酸、グリシン、アミノメチルリン酸、グアニジン、ジエチレントリアミン、トリス（２－アミノエチル）アミン、４－メルカプトブタン酸、３－アミノプロパノール、３－メルカプトプロパノール、Ｎ－（３－アミノプロピル）－１，３－プロパンジアミン、３－（ビス（３－アミノプロピル）アミノ）プロパン－１－オール、１－チオグリセロール、ジメルカプロール、１－メルカプト－２－ブタノール、１－メルカプト－２－ペンタノール、３－メルカプト－１－プロパノール、２，３－ジメルカプト－１－プロパノール、ジエタノールアミン、２－（２－アミノエチル）アミノエタノール、ジメチレントリアミン、１，１－オキシビスメチルアミン、１，１－チオビスメチルアミン、２－［（２－アミノエチル）アミノ］エタンチオール、ビス（２－メルカプトエチル）アミン、２－アミノエタン－１－チオール、１－アミノ－２－ブタノール、１－アミノ－２－ペンタノール、Ｌ－システイン、Ｄ－システイン、３－アミノ－１－プロパノール、Ｌ－ホモセリン、Ｄ－ホモセリン、アミノヒドロキシ酢酸、Ｌ－乳酸、Ｄ－乳酸、Ｌ－リンゴ酸、Ｄ－リンゴ酸、グリセリン酸、２－ヒドロキシ酪酸、Ｌ－酒石酸、Ｄ－酒石酸、タルトロン酸およびこれらの誘導体が挙げられる。 Specific examples of polydentate ligands include 3-mercaptopropionic acid, thioglycolic acid, 2-aminoethanol, 2-aminoethanediol, 2-mercaptoethanol, glycolic acid, ethylene glycol, ethylenediamine, aminosulfonic acid, and glycine. , Aminomethylphosphate, guanidine, diethylenetriamine, tris (2-aminoethyl) amine, 4-mercaptobutanoic acid, 3-aminopropanol, 3-mercaptopropanol, N- (3-aminopropyl) -1,3-propanediamine , 3- (Bis (3-aminopropyl) amino) propan-1-ol, 1-thioglycerol, dimercaprol, 1-mercapto-2-butanol, 1-mercapto-2-pentanol, 3-mercapto-1 -Propanol, 2,3-dimercapto-1-propanol, diethanolamine, 2- (2-aminoethyl) aminoethanol, dimethylenetriamine, 1,1-oxybismethylamine, 1,1-thiobismethylamine, 2- [(2-Aminoethyl) amino] ethanethiol, bis (2-mercaptoethyl) amine, 2-aminoethane-1-thiol, 1-amino-2-butanol, 1-amino-2-pentanol, L-cysteine, D-cysteine, 3-amino-1-propanol, L-homoseline, D-homoseline, aminohydroxyacetic acid, L-lactic acid, D-lactic acid, L-apple acid, D-apple acid, glyceric acid, 2-hydroxybutyric acid, Examples thereof include L-tartrate acid, D-tartrate acid, tartronic acid and derivatives thereof.
　多座配位子としては、多座配位子とＰｂＳ量子ドットのＰｂ原子との間の錯安定定数Ｋ１が６以上である化合物が好ましく用いられる。多座配位子の上記錯安定定数Ｋ１は８以上であることがより好ましく、１０以上であることが更に好ましい。多座配位子と、ＰｂＳ量子ドットのＰｂ原子との間の錯安定定数Ｋ１が６以上であれば、ＰｂＳ量子ドットと多座配位子との結合の強さを高めることが出来る。 As the polydentate ligand, a compound having a complex stability constant K1 between the polydentate ligand and the Pb atom of the PbS quantum dot of 6 or more is preferably used. The complex stability constant K1 of the polydentate ligand is more preferably 8 or more, and further preferably 10 or more. When the complex stability constant K1 between the polydentate ligand and the Pb atom of the PbS quantum dot is 6 or more, the strength of the bond between the PbS quantum dot and the polydentate ligand can be increased.
　錯安定定数Ｋ１とは、配位子と配位結合の対象となる金属原子との関係で定まる定数であり、下記式（ｂ）により表される。 The complex stability constant K1 is a constant determined by the relationship between the ligand and the metal atom to be coordinated, and is represented by the following formula (b).
　錯安定定数Ｋ１＝［ＭＬ］／（［Ｍ］・［Ｌ］）　　　・・・（ｂ）
　式（ｂ）において、［ＭＬ］は、金属原子と配位子が結合した錯体のモル濃度を表し、［Ｍ］は配位結合に寄与する金属原子のモル濃度を表し、［Ｌ］は配位子のモル濃度を表す。 Complex stability constant K1 = [ML] / ([M] / [L]) ... (b)
In formula (b), [ML] represents the molar concentration of the complex in which the metal atom and the ligand are bonded, [M] represents the molar concentration of the metal atom contributing to the coordination bond, and [L] represents the molar concentration. Represents the molar concentration of the ligand.
　実際には一つの金属原子に複数の配位子が配位する場合もあるが、本発明では、一つの金属原子に一つの配位子分子が配位する場合の式（ｂ）で表される錯安定定数Ｋ１を、配位結合の強さの指標として規定する。 In reality, a plurality of ligands may be coordinated to one metal atom, but in the present invention, it is represented by the formula (b) when one ligand molecule is coordinated to one metal atom. The complex stability constant K1 is defined as an index of the strength of coordination bonds.
　配位子と金属原子との間の錯安定定数Ｋ１の求め方としては、分光法、磁気共鳴分光法、ポテンショメトリー、溶解度測定、クロマトグラフィー、カロリメトリー、凝固点測定、蒸気圧測定、緩和測定、粘度測定、表面張力測定等がある。本発明では様々な手法や研究機関からの結果がまとめられた、Ｓｃ－Ｄａｔａｂｅｓｅ　ｖｅｒ．５．８５（Ａｃａｄｅｍｉ　Ｓｏｆｔｗａｒｅ）（２０１０）を使用することで、錯安定定数Ｋ１を定めた。錯安定定数Ｋ１がＳｃ－Ｄａｔａｂｅｓｅ　ｖｅｒ．５．８５に無い場合には、Ａ．Ｅ．ＭａｒｔｅｌｌとＲ．Ｍ．Ｓｍｉｔｈ著、Ｃｒｉｔｉｃａｌ　Ｓｔａｂｉｌｉｔｙ　Ｃｏｎｓｔａｎｔｓに記載の値を用いる。Ｃｒｉｔｉｃａｌ　Ｓｔａｂｉｌｉｔｙ　Ｃｏｎｓｔａｎｔｓにも錯安定定数Ｋ１が記載されていない場合は、既述の測定方法を用いるか、錯安定定数Ｋ１を計算するプログラムＰＫＡＳ法（Ａ．Ｅ．Ｍａｒｔｅｌｌら著、Ｔｈｅ　Ｄｅｔｅｒｍｉｎａｔｉｏｎ　ａｎｄ　Ｕｓｅ　ｏｆ　Ｓｔａｂｉｌｉｔｙ　Ｃｏｎｓｔａｎｔｓ，ＶＣＨ（１９８８））を用いて、錯安定定数Ｋ１を算出する。 The complex stability constant K1 between the ligand and the metal atom can be obtained by spectroscopy, magnetic resonance spectroscopy, potentiometry, solubility measurement, chromatography, calorimetry, freezing point measurement, vapor pressure measurement, relaxation measurement, and viscosity. There are measurement, surface tension measurement, etc. In the present invention, Sc-Database ver., Which summarizes the results from various methods and research institutes. The complex stability constant K1 was determined by using 5.85 (Academi Software) (2010). The complex stability constant K1 is Sc-Database ver. If it is not in 5.85, A. E. Martell and R.M. M. The values described in Critical Stability Constants by Smith are used. If the complex stability constant K1 is not described in the Critical Stability Constants, either use the measurement method described above or use the program PKAS method for calculating the complex stability constant K1 (by AE Martell et al., The Determination and Use of). Stability Constants, VCH (1988)) is used to calculate the complex stability constant K1.
　ＰｂＳ量子ドットの集合体と、ＰｂＳ量子ドットに配位する配位子とを含む光電変換層は、Ｓ原子１モルに対してＰｂ原子を１．７５モル以上１．９５モル以下含むＰｂＳ量子ドットと、ＰｂＳ量子ドットに配位する配位子と、溶剤とを含む分散液を基板上に付与して、ＰｂＳ量子ドットの集合体の膜を形成する工程（ＰｂＳ量子ドット集合体形成工程）を経て形成することが好ましい。すなわち、本発明の光検出素子の製造方法は、Ｓ原子１モルに対してＰｂ原子を１．７５モル以上１．９５モル以下含むＰｂＳ量子ドットと、ＰｂＳ量子ドットに配位する配位子と、溶剤と、を含む分散液を用いてＰｂＳ量子ドットの集合体の膜を形成する工程を含むことが好ましい。
　分散液を基板上に付与する手法は、特に限定はない。スピンコート法、ディップ法、インクジェット法、ディスペンサー法、スクリーン印刷法、凸版印刷法、凹版印刷法、スプレーコート法等の塗布方法が挙げられる。 The photoelectric conversion layer containing an aggregate of PbS quantum dots and a ligand coordinating to the PbS quantum dots is a PbS quantum dot containing 1.75 mol or more and 1.95 mol or less of Pb atom with respect to 1 mol of S atom. A step of applying a dispersion liquid containing a ligand coordinating to the PbS quantum dots and a solvent on the substrate to form a film of the aggregates of the PbS quantum dots (PbS quantum dot aggregate forming step). It is preferable to form through. That is, in the method for manufacturing a photodetection device of the present invention, a PbS quantum dot containing 1.75 mol or more and 1.95 mol or less of a Pb atom with respect to 1 mol of S atom and a ligand coordinating to the PbS quantum dot It is preferable to include a step of forming a film of an aggregate of PbS quantum dots using a dispersion liquid containing, and a solvent.
The method of applying the dispersion liquid on the substrate is not particularly limited. Examples thereof include a spin coating method, a dip method, an inkjet method, a dispenser method, a screen printing method, a letterpress printing method, an intaglio printing method, and a spray coating method.
　また、ＰｂＳ量子ドットの集合体の膜を形成した後、更に配位子交換工程を行ってＰｂＳ量子ドットに配位している配位子を他の配位子に交換してもよい。配位子交換工程では、ＰｂＳ量子ドット集合体形成工程によって形成されたＰｂＳ量子ドットの集合体の膜に対して、配位子Ａおよび溶剤を含む配位子溶液を付与して、ＰｂＳ量子ドットに配位している配位子を配位子Ａに交換する。配位子Ａは２種以上の配位子を含んでいてもよく、配位子溶液は２種併用してもよい。配位子Ａとしては、上述したハロゲン原子を含む配位子や配位部を２以上含む多座配位子が挙げられる。 Further, after forming a film of an aggregate of PbS quantum dots, a ligand exchange step may be further performed to exchange the ligand coordinated with the PbS quantum dots with another ligand. In the ligand exchange step, a ligand solution containing the ligand A and the solvent is applied to the membrane of the PbS quantum dot aggregate formed by the PbS quantum dot aggregate forming step, and the PbS quantum dot is added. The ligand coordinated with is exchanged for the ligand A. The ligand A may contain two or more kinds of ligands, and two kinds of ligand solutions may be used in combination. Examples of the ligand A include the above-mentioned ligand containing a halogen atom and a polydentate ligand containing two or more coordination portions.
　一方で、分散液において、ＰｂＳ量子ドットの表面にあらかじめ所望の配位子を付与させておき、この分散液を基板上に塗布して光電変換層を形成してもよい。 On the other hand, in the dispersion liquid, a desired ligand may be imparted to the surface of the PbS quantum dots in advance, and this dispersion liquid may be applied onto the substrate to form a photoelectric conversion layer.
　分散液中のＰｂＳ量子ドットの含有量は、１～５００ｍｇ／ｍＬであることが好ましく、１０～２００ｍｇ／ｍＬであることがより好ましく、２０～１００ｍｇ／ｍＬであることが更に好ましい。 The content of PbS quantum dots in the dispersion is preferably 1 to 500 mg / mL, more preferably 10 to 200 mg / mL, and even more preferably 20 to 100 mg / mL.
　分散液や配位子溶液に含まれる溶剤としては、エステル系溶剤、ケトン系溶剤、アルコール系溶剤、アミド系溶剤、エーテル系溶剤、炭化水素系溶剤などが挙げられる。これらの詳細については、国際公開第２０１５／１６６７７９号の段落番号０２２３を参酌でき、この内容は本明細書に組み込まれる。また、環状アルキル基が置換したエステル系溶剤、環状アルキル基が置換したケトン系溶剤を用いることもできる。溶剤の金属不純物は少ないほうが好ましく、金属含有量は、例えば１０質量ｐｐｂ（ｐａｒｔｓ　ｐｅｒ　ｂｉｌｌｉｏｎ）以下である。必要に応じて質量ｐｐｔ（ｐａｒｔｓ　ｐｅｒ　ｔｒｉｌｌｉｏｎ）レベルの溶剤を用いてもよく、そのような溶剤は例えば東洋合成社が提供している（化学工業日報、２０１５年１１月１３日）。溶剤から金属等の不純物を除去する方法としては、例えば、蒸留（分子蒸留や薄膜蒸留等）やフィルタを用いたろ過を挙げることができる。ろ過に用いるフィルタのフィルタ孔径としては、１０μｍ以下が好ましく、５μｍ以下がより好ましく、３μｍ以下が更に好ましい。フィルタの材質は、ポリテトラフロロエチレン、ポリエチレンまたはナイロンが好ましい。溶剤は、異性体（原子数が同じであるが構造が異なる化合物）が含まれていてもよい。また、異性体は、１種のみが含まれていてもよいし、複数種含まれていてもよい。 Examples of the solvent contained in the dispersion liquid and the ligand solution include ester-based solvents, ketone-based solvents, alcohol-based solvents, amide-based solvents, ether-based solvents, and hydrocarbon-based solvents. For these details, paragraph number 0223 of WO 2015/166779 can be referred to, the contents of which are incorporated herein by reference. Further, an ester solvent substituted with a cyclic alkyl group and a ketone solvent substituted with a cyclic alkyl group can also be used. It is preferable that the amount of metal impurities in the solvent is small, and the metal content is, for example, 10 mass ppb (parts per parts) or less. If necessary, a solvent at the mass ppt (parts per parts) level may be used, and such a solvent is provided by, for example, Toyo Synthetic Co., Ltd. (The Chemical Daily, November 13, 2015). Examples of the method for removing impurities such as metals from the solvent include distillation (molecular distillation, thin film distillation, etc.) and filtration using a filter. The filter pore diameter of the filter used for filtration is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less. The filter material is preferably polytetrafluoroethylene, polyethylene or nylon. The solvent may contain isomers (compounds having the same number of atoms but different structures). Further, only one kind of isomer may be contained, or a plurality of kinds may be contained.
　光検出素子の光電変換層の厚みは、１０～６００ｎｍであることが好ましく、５０～６００ｎｍであることがより好ましく、１００～６００ｎｍであることが更に好ましく、１５０～６００ｎｍであることがより一層好ましい。厚みの上限は、５５０ｎｍ以下が好ましく、５００ｎｍ以下がより好ましく、４５０ｎｍ以下が更に好ましい。 The thickness of the photoelectric conversion layer of the photodetector is preferably 10 to 600 nm, more preferably 50 to 600 nm, further preferably 100 to 600 nm, and even more preferably 150 to 600 nm. .. The upper limit of the thickness is preferably 550 nm or less, more preferably 500 nm or less, and even more preferably 450 nm or less.
光検出素子で検出する目的の波長の光に対する光電変換層の屈折率は２．０～３．０であることが好ましく、２．１～２．８であることがより好ましく、２．２～２．７であることが更に好ましい。この態様によれば、光検出素子をフォトダイオードの構成とした際において、高い光吸収率、すなわち高い外部量子効率を実現しやすくなる。 The refractive index of the photoelectric conversion layer with respect to light of the target wavelength detected by the photodetector is preferably 2.0 to 3.0, more preferably 2.1 to 2.8, and 2.2 to 2.8. It is more preferably 2.7. According to this aspect, when the photodetector is configured as a photodiode, it becomes easy to realize a high light absorption rate, that is, a high external quantum efficiency.
　本発明の光検出素子は、赤外域の波長の光に対して優れた感度を有しているので、赤外域の波長の光を検出するものであることが好ましい。すなわち、本発明の光検出素子は、赤外光検出素子であることが好ましい。また、上述した光検出素子で検出する目的の光は、赤外域の波長の光であることが好ましい。また、赤外域の波長の光は、波長７００ｎｍを超える波長の光であることが好ましく、波長８００ｎｍ以上の光であることがより好ましく、波長９００ｎｍ以上の光であることが更に好ましい。また、赤外域の波長の光は、波長２０００ｎｍ以下の光であることが好ましく、波長１６００ｎｍ以下の光であることがより好ましい。 Since the photodetector of the present invention has excellent sensitivity to light having a wavelength in the infrared region, it is preferable to detect light having a wavelength in the infrared region. That is, the photodetection element of the present invention is preferably an infrared light detection element. Further, the target light to be detected by the above-mentioned photodetector is preferably light having a wavelength in the infrared region. Further, the light having a wavelength in the infrared region is preferably light having a wavelength exceeding 700 nm, more preferably light having a wavelength of 800 nm or more, and further preferably light having a wavelength of 900 nm or more. Further, the light having a wavelength in the infrared region is preferably light having a wavelength of 2000 nm or less, and more preferably light having a wavelength of 1600 nm or less.
　また、本発明の光検出素子は、赤外域の波長の光と、可視域の波長の光（好ましくは波長４００～７００ｎｍの範囲の光）とを同時に検出するものであってもよい。 Further, the light detection element of the present invention may simultaneously detect light having a wavelength in the infrared region and light having a wavelength in the visible region (preferably light having a wavelength in the range of 400 to 700 nm).
　光検出素子の種類としては、フォトコンダクタ型の光検出素子、フォトダイオード型の光検出素子が挙げられる。なかでも、高い信号ノイズ比（ＳＮ比）が得られやすいという理由からフォトダイオード型の光検出素子であることが好ましい。 Examples of the type of photodetector include a photoconductor type photodetector and a photodiode type photodetector. Of these, a photodiode-type photodetector is preferable because a high signal-to-noise ratio (SN ratio) can be easily obtained.
　図１に、フォトダイオード型の光検出素子の一実施形態を示す。なお、図中の矢印は光検出素子への入射光を表す。図１に示す光検出素子１は、下部電極１２と、下部電極１２に対向する上部電極１１と、下部電極１２と上部電極１１との間に設けられた光電変換層１３とを含んでいる。図１に示す光検出素子１は、上部電極１１の上方から光を入射して用いられる。 FIG. 1 shows an embodiment of a photodiode-type photodetector. The arrows in the figure represent the incident light on the photodetector. The photodetection element 1 shown in FIG. 1 includes a lower electrode 12, an upper electrode 11 facing the lower electrode 12, and a photoelectric conversion layer 13 provided between the lower electrode 12 and the upper electrode 11. The photodetection element 1 shown in FIG. 1 is used by injecting light from above the upper electrode 11.
　光電変換層１３は上述した本発明に係る光電変換層である。光電変換層の好ましい態様については上述した通りである。 The photoelectric conversion layer 13 is the photoelectric conversion layer according to the present invention described above. The preferred embodiment of the photoelectric conversion layer is as described above.
　また、光検出素子で検出する目的の光の波長λと、下部電極１２の光電変換層１３側の表面１２ａから、光電変換層１３の上部電極層側の表面１３ａまでの上記波長λの光の光路長Ｌλとが下記式（１－１）の関係を満していることが好ましく、下記式（１－２）の関係を満していることがより好ましい。波長λと光路長Ｌλとがこのような関係を満たしている場合には、光電変換層１３において、上部電極１１側から入射された光（入射光）と、下部電極１２の表面で反射された光（反射光）との位相を揃えることができ、その結果、光学干渉効果によって光が強め合い、より高い外部量子効率を得ることができる。 Further, the wavelength λ of the target light to be detected by the photodetector and the light having the wavelength λ from the surface 12a of the lower electrode 12 on the photoelectric conversion layer 13 side to the surface 13a of the photoelectric conversion layer 13 on the upper electrode layer side. It is preferable that the optical path length L λ satisfies the relationship of the following equation (1-1), and more preferably the relationship of the following equation (1-2) is satisfied. When the wavelength λ and the optical path length L λ satisfy such a relationship, the light (incident light) incident from the upper electrode 11 side is reflected by the surface of the lower electrode 12 in the photoelectric conversion layer 13. It is possible to align the phase with the light (reflected light), and as a result, the light is strengthened by the optical interference effect, and higher external quantum efficiency can be obtained.
　０．０５＋ｍ／２≦Ｌλ／λ≦０．３５＋ｍ／２　　　・・・（１－１）
　０．１０＋ｍ／２≦Ｌλ／λ≦０．３０＋ｍ／２　　　・・・（１－２） 0.05 + m / 2 ≤ L λ / λ ≤ 0.35 + m / 2 ... (1-1)
0.10 + m / 2 ≤ L λ / λ ≤ 0.30 + m / 2 ... (1-2)
　上記式中、λは、光検出素子で検出する目的の光の波長であり、
　Ｌλは、下部電極１２の光電変換層１３側の表面１２ａから、光電変換層１３の上部電極層側の表面１３ａまでの波長λの光の光路長であり、
　ｍは０以上の整数である。 In the above equation, λ is the wavelength of the target light to be detected by the photodetector.
L λ is the optical path length of light having a wavelength λ from the surface 12a on the photoelectric conversion layer 13 side of the lower electrode 12 to the surface 13a on the upper electrode layer side of the photoelectric conversion layer 13.
m is an integer greater than or equal to 0.
　ｍは０～４の整数であることが好ましく、０～３の整数であることがより好ましく、０～２の整数であることが更に好ましい。この態様によれば、正孔や電子などの電荷の輸送特性が良好であり、光検出素子の外部量子効率をより高めることができる。 M is preferably an integer of 0 to 4, more preferably an integer of 0 to 3, and even more preferably an integer of 0 to 2. According to this aspect, the transport characteristics of charges such as holes and electrons are good, and the external quantum efficiency of the photodetection device can be further enhanced.
　ここで、光路長とは、光が透過する物質の物理的な厚みと屈折率を乗じたものを意味する。光電変換層１３を例に挙げて説明すると、光電変換層の厚さをｄ１、光電変換層の波長λ１に対する屈折率をＮ１としたとき、光電変換層１３を透過する波長λ１の光の光路長はＮ１×ｄ１である。光電変換層１３が２層以上の積層膜で構成されている場合や、光電変換層１３と下部電極１２との間に後述する中間層が存在する場合には、各層の光路長の積算値が上記光路長Ｌλである。 Here, the optical path length means the product of the physical thickness of the substance through which light is transmitted and the refractive index. Taking the photoelectric conversion layer 13 as an example, when the thickness of the photoelectric conversion layer is d 1 and the refractive index of the photoelectric conversion layer with respect to the wavelength λ 1 is N 1 , the wavelength λ 1 transmitted through the photoelectric conversion layer 13 The optical path length of light is N 1 × d 1 . When the photoelectric conversion layer 13 is composed of two or more laminated films, or when an intermediate layer described later is present between the photoelectric conversion layer 13 and the lower electrode 12, the integrated value of the optical path length of each layer is calculated. The optical path length L λ .
　上部電極１１は、光検出素子で検出する目的の光の波長に対して実質的に透明な導電材料で形成された透明電極であることが好ましい。なお、本発明において、「実質的に透明である」とは、透過率が５０％以上であることを意味し、６０％以上が好ましく、８０％以上が特に好ましい。上部電極１１の材料としては、導電性金属酸化物などが挙げられる。具体例としては、酸化錫、酸化亜鉛、酸化インジウム、酸化インジウムタングステン、酸化インジウム亜鉛（ｉｎｄｉｕｍ　ｚｉｎｃ　ｏｘｉｄｅ：ＩＺＯ）、酸化インジウム錫（ｉｎｄｉｕｍ　ｔｉｎ　ｏｘｉｄｅ：ＩＴＯ）、フッ素をドープした酸化錫（ｆｌｕｏｒｉｎｅ－ｄｏｐｅｄ　ｔｉｎ　ｏｘｉｄｅ：ＦＴＯ）等が挙げられる。 The upper electrode 11 is preferably a transparent electrode formed of a conductive material that is substantially transparent to the wavelength of the target light detected by the photodetector. In the present invention, "substantially transparent" means that the transmittance is 50% or more, preferably 60% or more, and particularly preferably 80% or more. Examples of the material of the upper electrode 11 include a conductive metal oxide. Specific examples include tin oxide, zinc oxide, indium oxide, indium tungsten oxide, indium zinc oxide (IZO), indium tin oxide (ITO), and fluorine-doped tin oxide (fluorine-topped). Tin oxide: FTO) and the like.
　上部電極１１の膜厚は、特に限定されず、０．０１～１００μｍが好ましく、０．０１～１０μｍがさらに好ましく、０．０１～１μｍが特に好ましい。なお、本発明において、各層の膜厚は、走査型電子顕微鏡（ｓｃａｎｎｉｎｇ　ｅｌｅｃｔｒｏｎ　ｍｉｃｒｏｓｃｏｐｅ：ＳＥＭ）等を用いて光検出素子１の断面を観察することにより、測定できる。 The film thickness of the upper electrode 11 is not particularly limited, and is preferably 0.01 to 100 μm, more preferably 0.01 to 10 μm, and particularly preferably 0.01 to 1 μm. In the present invention, the thickness of each layer can be measured by observing the cross section of the light detection element 1 using a scanning electron microscope (SEM) or the like.
　下部電極１２を形成する材料としては、例えば、白金、金、ニッケル、銅、銀、インジウム、ルテニウム、パラジウム、ロジウム、イリジウム、オスニウム、アルミニウム等の金属、上述の導電性金属酸化物、炭素材料および導電性高分子等が挙げられる。炭素材料としては、導電性を有する材料であればよく、例えば、フラーレン、カーボンナノチューブ、グラファイト、グラフェン等が挙げられる。 Examples of the material forming the lower electrode 12 include metals such as platinum, gold, nickel, copper, silver, indium, ruthenium, palladium, rhodium, iridium, osnium, and aluminum, the above-mentioned conductive metal oxides, carbon materials, and the like. Examples include conductive polymers. The carbon material may be any material having conductivity, and examples thereof include fullerenes, carbon nanotubes, graphite, graphene and the like.
　下部電極１２としては、金属もしくは導電性金属酸化物の薄膜（蒸着してなる薄膜を含む）、または、この薄膜を有するガラス基板もしくはプラスチック基板が好ましい。ガラス基板もしくはプラスチック基板としては、金もしくは白金の薄膜を有するガラス、または、白金を蒸着したガラスが好ましい。下部電極１２の膜厚は、特に限定されず、０．０１～１００μｍが好ましく、０．０１～１０μｍがさらに好ましく、０．０１～１μｍが特に好ましい。 As the lower electrode 12, a thin film of metal or a conductive metal oxide (including a thin film formed by vapor deposition), or a glass substrate or a plastic substrate having this thin film is preferable. As the glass substrate or the plastic substrate, glass having a thin film of gold or platinum or glass on which platinum is vapor-deposited is preferable. The film thickness of the lower electrode 12 is not particularly limited, and is preferably 0.01 to 100 μm, more preferably 0.01 to 10 μm, and particularly preferably 0.01 to 1 μm.
　なお、図示しないが、上部電極１１の光入射側の表面（光電変換層１３側とは反対の表面）には透明基板が配置されていてもよい。透明基板の種類としては、ガラス基板、樹脂基板、セラミック基板等が挙げられる。 Although not shown, a transparent substrate may be arranged on the surface of the upper electrode 11 on the light incident side (the surface opposite to the photoelectric conversion layer 13 side). Examples of the type of transparent substrate include a glass substrate, a resin substrate, and a ceramic substrate.
　また、図示しないが、光電変換層１３と下部電極１２との間、および／または、光電変換層１３と上部電極１１との間には中間層が設けられていてもよい。中間層としては、ブロッキング層、電子輸送層、正孔輸送層などが挙げられる。好ましい形態としては、光電変換層１３と下部電極１２との間、および、光電変換層１３と上部電極１１との間のいずれか一方に正孔輸送層を有する態様が挙げられる。光電変換層１３と下部電極１２との間、および、光電変換層１３と上部電極１１との間のいずれか一方には電子輸送層を有し、他方には正孔輸送層を有することがより好ましい。正孔輸送層および電子輸送層は単層膜であってもよく、２層以上の積層膜であってもよい。 Further, although not shown, an intermediate layer may be provided between the photoelectric conversion layer 13 and the lower electrode 12 and / or between the photoelectric conversion layer 13 and the upper electrode 11. Examples of the intermediate layer include a blocking layer, an electron transport layer, and a hole transport layer. A preferred embodiment includes a mode in which the hole transport layer is provided between the photoelectric conversion layer 13 and the lower electrode 12 and between the photoelectric conversion layer 13 and the upper electrode 11. It is possible that one of the photoelectric conversion layer 13 and the lower electrode 12 and one of the photoelectric conversion layer 13 and the upper electrode 11 has an electron transport layer and the other has a hole transport layer. preferable. The hole transport layer and the electron transport layer may be a single-layer film or a laminated film having two or more layers.
　ブロッキング層は逆電流を防止する機能を有する層である。ブロッキング層は短絡防止層ともいう。ブロッキング層を形成する材料は、例えば、酸化ケイ素、酸化マグネシウム、酸化アルミニウム、炭酸カルシウム、炭酸セシウム、ポリビニルアルコール、ポリウレタン、酸化チタン、酸化スズ、酸化亜鉛、酸化ニオブ、酸化タングステン等が挙げられる。ブロッキング層は単層膜であってもよく、２層以上の積層膜であってもよい。 The blocking layer is a layer having a function of preventing reverse current. The blocking layer is also called a short circuit prevention layer. Examples of the material forming the blocking layer include silicon oxide, magnesium oxide, aluminum oxide, calcium carbonate, cesium carbonate, polyvinyl alcohol, polyurethane, titanium oxide, tin oxide, zinc oxide, niobium oxide, tungsten oxide and the like. The blocking layer may be a single-layer film or a laminated film having two or more layers.
　電子輸送層は、光電変換層１３で発生した電子を上部電極１１または下部電極１２へと輸送する機能を有する層である。電子輸送層は正孔ブロック層ともいわれている。電子輸送層は、この機能を発揮することができる電子輸送材料で形成される。電子輸送材料としては、［６，６］－Ｐｈｅｎｙｌ－Ｃ６１－Ｂｕｔｙｒｉｃ　Ａｃｉｄ　Ｍｅｔｈｙｌ　Ｅｓｔｅｒ（ＰＣ６１ＢＭ）等のフラーレン化合物、ペリレンテトラカルボキシジイミド等のペリレン化合物、テトラシアノキノジメタン、酸化チタン、酸化錫、酸化亜鉛、酸化インジウム、酸化インジウムタングステン、酸化インジウム亜鉛、酸化インジウム錫、フッ素をドープした酸化錫等が挙げられる。電子輸送層は単層膜であってもよく、２層以上の積層膜であってもよい。 The electron transport layer is a layer having a function of transporting electrons generated in the photoelectric conversion layer 13 to the upper electrode 11 or the lower electrode 12. The electron transport layer is also called a hole block layer. The electron transport layer is formed of an electron transport material capable of exerting this function. Examples of the electron transporting material include fullerene compounds such as [6,6] -Phenyl-C61-Butyric Acid Metyl Ester (PC 61 BM), perylene compounds such as perylene tetracarboxydiimide, tetracyanoquinodimethane, titanium oxide, and tin oxide. , Zinc oxide, indium oxide, indium tungsten oxide, indium zinc oxide, indium tin oxide, fluorine-doped tin oxide and the like. The electron transport layer may be a single-layer film or a laminated film having two or more layers.
　正孔輸送層は、光電変換層１３で発生した正孔を上部電極１１または下部電極１２へと輸送する機能を有する層である。正孔輸送層は電子ブロック層ともいわれている。正孔輸送層は、この機能を発揮することができる正孔輸送材料で形成されている。例えば、ＰＥＤＯＴ：ＰＳＳ（ポリ（３，４－エチレンジオキシチオフェン）：ポリ（４－スチレンスルホン酸））、ＭｏＯ３などが挙げられる。また、特開２００１－２９１５３４号公報の段落番号０２０９～０２１２に記載の有機正孔輸送材料等を用いることもできる。また、正孔輸送材料には半導体量子ドットを用いることもできる。半導体量子ドットを構成する半導体量子ドット材料としては、例えば一般的な半導体結晶〔ａ）ＩＶ族半導体、ｂ）ＩＶ－ＩＶ族、ＩＩＩ－Ｖ族、またはＩＩ－ＶＩ族の化合物半導体、ｃ）ＩＩ族、ＩＩＩ族、ＩＶ族、Ｖ族、および、ＶＩ族元素の内３つ以上の組み合わせからなる化合物半導体〕
のナノ粒子（０．５ｎｍ以上１００ｎｍ未満大の粒子）が挙げられる。具体的には、ＰｂＳ、ＰｂＳｅ、ＩｎＮ、ＩｎＡｓ、Ｇｅ、ＩｎＡｓ、ＩｎＧａＡｓ、ＣｕＩｎＳ、ＣｕＩｎＳｅ、ＣｕＩｎＧａＳｅ、ＩｎＳｂ、Ｓｉ、ＩｎＰ等の比較的バンドギャップの狭い半導体材料が挙げられる。半導体量子ドットの表面には配位子が配位していてもよい。配位子としては上述した多座配位子などが挙げられる。 The hole transport layer is a layer having a function of transporting holes generated in the photoelectric conversion layer 13 to the upper electrode 11 or the lower electrode 12. The hole transport layer is also called an electron block layer. The hole transport layer is formed of a hole transport material capable of exerting this function. For example, PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (4-styrenesulfonic acid)), MoO 3 and the like can be mentioned. Further, the organic hole transport material or the like described in paragraph Nos. 0209 to 0212 of JP-A-2001-291534 can also be used. Further, semiconductor quantum dots can also be used as the hole transport material. Examples of the semiconductor quantum dot material constituting the semiconductor quantum dot include general semiconductor crystals [a) group IV semiconductors, b) group IV-IV, group III-V, or group II-VI compound semiconductors, c) II. A compound semiconductor consisting of a combination of three or more of Group III, Group IV, Group V, and Group VI elements]
Nanoparticles (particles having a size of 0.5 nm or more and less than 100 nm) can be mentioned. Specific examples thereof include semiconductor materials having a relatively narrow bandgap, such as PbS, PbSe, InN, InAs, Ge, InAs, InGaAs, CuInS, CuInSe, CuInGaSe, InSb, Si, and InP. A ligand may be coordinated on the surface of the semiconductor quantum dot. Examples of the ligand include the polydentate ligand described above.
＜イメージセンサ＞
　本発明のイメージセンサは、上述した本発明の光検出素子を含む。イメージセンサの構成としては、本発明の光検出素子を備え、イメージセンサとして機能する構成であれば特に限定はない。 <Image sensor>
The image sensor of the present invention includes the above-mentioned photodetector of the present invention. The configuration of the image sensor is not particularly limited as long as it includes the photodetector of the present invention and functions as an image sensor.
　本発明のイメージセンサは、赤外線透過フィルタ層を含んでいてもよい。赤外線透過フィルタ層としては、可視域の波長帯域の光の透過性が低いものであることが好ましく、波長４００～６５０ｎｍの範囲の光の平均透過率が１０％以下であることがより好ましく、７．５％以下であることが更に好ましく、５％以下であることが特に好ましい。 The image sensor of the present invention may include an infrared transmission filter layer. The infrared transmission filter layer preferably has low light transmittance in the visible wavelength band, and more preferably has an average transmittance of light in the wavelength range of 400 to 650 nm of 10% or less. It is more preferably 5.5% or less, and particularly preferably 5% or less.
　赤外線透過フィルタ層としては、色材を含む樹脂膜で構成されたものなどが挙げられる。色材としては、赤色色材、緑色色材、青色色材、黄色色材、紫色色材、オレンジ色色材などの有彩色色材、黒色色材が挙げられる。赤外線透過フィルタ層に含まれる色材は、２種以上の有彩色色材の組み合わせで黒色を形成しているか、黒色色材を含むものであることが好ましい。２種以上の有彩色色材の組み合わせで黒色を形成する場合の、有彩色色材の組み合わせとしては、例えば以下の（Ｃ１）～（Ｃ７）の態様が挙げられる。
　（Ｃ１）赤色色材と青色色材とを含有する態様。
　（Ｃ２）赤色色材と青色色材と黄色色材とを含有する態様。
　（Ｃ３）赤色色材と青色色材と黄色色材と紫色色材とを含有する態様。
　（Ｃ４）赤色色材と青色色材と黄色色材と紫色色材と緑色色材とを含有する態様。
　（Ｃ５）赤色色材と青色色材と黄色色材と緑色色材とを含有する態様。
　（Ｃ６）赤色色材と青色色材と緑色色材とを含有する態様。
　（Ｃ７）黄色色材と紫色色材とを含有する態様。 Examples of the infrared transmission filter layer include those composed of a resin film containing a coloring material. Examples of the coloring material include chromatic color materials such as red color material, green color material, blue color material, yellow color material, purple color material, and orange color material, and black color material. The color material contained in the infrared transmission filter layer is preferably a combination of two or more kinds of chromatic color materials to form black, or preferably contains a black color material. Examples of the combination of chromatic color materials in the case of forming black by combining two or more kinds of chromatic color materials include the following aspects (C1) to (C7).
(C1) An embodiment containing a red color material and a blue color material.
(C2) An embodiment containing a red color material, a blue color material, and a yellow color material.
(C3) An embodiment containing a red color material, a blue color material, a yellow color material, and a purple color material.
(C4) An embodiment containing a red color material, a blue color material, a yellow color material, a purple color material, and a green color material.
(C5) An embodiment containing a red color material, a blue color material, a yellow color material, and a green color material.
(C6) An embodiment containing a red color material, a blue color material, and a green color material.
(C7) An embodiment containing a yellow color material and a purple color material.
　上記有彩色色材は、顔料であってもよく、染料であってもよい。顔料と染料とを含んでいてもよい。黒色色材は、有機黒色色材であることが好ましい。例えば、有機黒色色材としては、ビスベンゾフラノン化合物、アゾメチン化合物、ペリレン化合物、アゾ化合物などが挙げられる。 The chromatic color material may be a pigment or a dye. Pigments and dyes may be included. The black color material is preferably an organic black color material. For example, examples of the organic black color material include a bisbenzofuranone compound, an azomethine compound, a perylene compound, and an azo compound.
　赤外線透過フィルタ層はさらに赤外線吸収剤を含有していてもよい。赤外線透過フィルタ層に赤外線吸収剤を含有させることで透過させる光の波長をより長波長側にシフトさせることができる。赤外線吸収剤としては、ピロロピロール化合物、シアニン化合物、スクアリリウム化合物、フタロシアニン化合物、ナフタロシアニン化合物、クアテリレン化合物、メロシアニン化合物、クロコニウム化合物、オキソノール化合物、イミニウム化合物、ジチオール化合物、トリアリールメタン化合物、ピロメテン化合物、アゾメチン化合物、アントラキノン化合物、ジベンゾフラノン化合物、ジチオレン金属錯体、金属酸化物、金属ホウ化物等が挙げられる。 The infrared transmission filter layer may further contain an infrared absorber. By including the infrared absorber in the infrared transmission filter layer, the wavelength of the transmitted light can be shifted to the longer wavelength side. Examples of infrared absorbers include pyrolopyrrole compounds, cyanine compounds, squarylium compounds, phthalocyanine compounds, naphthalocyanine compounds, quaterylene compounds, merocyanine compounds, croconium compounds, oxonor compounds, iminium compounds, dithiol compounds, triarylmethane compounds, pyromethene compounds, and azomethine compounds. Examples thereof include compounds, anthraquinone compounds, dibenzofuranone compounds, dithiolene metal complexes, metal oxides, and metal boroides.
　赤外線透過フィルタ層の分光特性については、イメージセンサの用途に応じて適宜選択することができる。例えば、以下の（１）～（５）のいずれかの分光特性を満たしているフィルタ層などが挙げられる。
　（１）：膜の厚み方向における光の透過率の、波長４００～７５０ｎｍの範囲における最大値が２０％以下（好ましくは１５％以下、より好ましくは１０％以下）で、膜の厚み方向における光の透過率の、波長９００～１５００ｎｍの範囲における最小値が７０％以上（好ましくは７５％以上、より好ましくは８０％以上）であるフィルタ層。
　（２）：膜の厚み方向における光の透過率の、波長４００～８３０ｎｍの範囲における最大値が２０％以下（好ましくは１５％以下、より好ましくは１０％以下）で、膜の厚み方向における光の透過率の、波長１０００～１５００ｎｍの範囲における最小値が７０％以上（好ましくは７５％以上、より好ましくは８０％以上）であるフィルタ層。
　（３）：膜の厚み方向における光の透過率の、波長４００～９５０ｎｍの範囲における最大値が２０％以下（好ましくは１５％以下、より好ましくは１０％以下）で、膜の厚み方向における光の透過率の、波長１１００～１５００ｎｍの範囲における最小値が７０％以上（好ましくは７５％以上、より好ましくは８０％以上）であるフィルタ層。
　（４）：膜の厚み方向における光の透過率の、波長４００～１１００ｎｍの範囲における最大値が２０％以下（好ましくは１５％以下、より好ましくは１０％以下）で、波長１４００～１５００ｎｍの範囲における最小値が７０％以上（好ましくは７５％以上、より好ましくは８０％以上）であるフィルタ層。
　（５）：膜の厚み方向における光の透過率の、波長４００～１３００ｎｍの範囲における最大値が２０％以下（好ましくは１５％以下、より好ましくは１０％以下）で、波長１６００～２０００ｎｍの範囲における最小値が７０％以上（好ましくは７５％以上、より好ましくは８０％以上）であるフィルタ層。 The spectral characteristics of the infrared transmission filter layer can be appropriately selected according to the application of the image sensor. For example, a filter layer satisfying any of the following spectral characteristics (1) to (5) can be mentioned.
(1): The maximum value of the light transmittance in the film thickness direction in the wavelength range of 400 to 750 nm is 20% or less (preferably 15% or less, more preferably 10% or less), and the light in the film thickness direction. A filter layer having a minimum value of 70% or more (preferably 75% or more, more preferably 80% or more) in the wavelength range of 900 to 1500 nm.
(2): The maximum value of the light transmittance in the film thickness direction in the wavelength range of 400 to 830 nm is 20% or less (preferably 15% or less, more preferably 10% or less), and the light in the film thickness direction. A filter layer having a minimum value of 70% or more (preferably 75% or more, more preferably 80% or more) in the wavelength range of 1000 to 1500 nm.
(3): The maximum value of the light transmittance in the film thickness direction in the wavelength range of 400 to 950 nm is 20% or less (preferably 15% or less, more preferably 10% or less), and the light in the film thickness direction. A filter layer having a minimum value in the wavelength range of 1100 to 1500 nm of 70% or more (preferably 75% or more, more preferably 80% or more).
(4): The maximum value of the light transmittance in the film thickness direction in the wavelength range of 400 to 1100 nm is 20% or less (preferably 15% or less, more preferably 10% or less), and the wavelength range is 1400 to 1500 nm. A filter layer having a minimum value of 70% or more (preferably 75% or more, more preferably 80% or more).
(5): The maximum value of the light transmittance in the film thickness direction in the wavelength range of 400 to 1300 nm is 20% or less (preferably 15% or less, more preferably 10% or less), and the wavelength range is 1600 to 2000 nm. A filter layer having a minimum value of 70% or more (preferably 75% or more, more preferably 80% or more).
　また、赤外線透過フィルタとして、特開２０１３－０７７００９号公報、特開２０１４－１３０１７３号公報、特開２０１４－１３０３３８号公報、国際公開第２０１５／１６６７７９号、国際公開第２０１６／１７８３４６号、国際公開第２０１６／１９０１６２号、国際公開第２０１８／０１６２３２号、特開２０１６－１７７０７９号公報、特開２０１４－１３０３３２号公報、国際公開第２０１６／０２７７９８号に記載の膜を用いることができる。また、赤外線透過フィルタは２つ以上のフィルタを組み合わせて用いてもよく、１つのフィルタで特定の２つ以上の波長領域を透過するデュアルバンドパスフィルタを用いてもよい。 Further, as infrared transmission filters, Japanese Patent Application Laid-Open No. 2013-077009, Japanese Patent Application Laid-Open No. 2014-130173, Japanese Patent Application Laid-Open No. 2014-130338, International Publication No. 2015/166779, International Publication No. 2016/178346, International Publication No. The films described in 2016/190162, International Publication No. 2018/016232, JP-A-2016-177079, JP-A-2014-130332, and International Publication No. 2016/0277798 can be used. Further, the infrared transmission filter may be used in combination of two or more filters, or a dual bandpass filter that transmits a specific two or more wavelength regions with one filter may be used.
　本発明のイメージセンサは、ノイズ低減などの各種性能を向上させる目的で赤外線遮蔽フィルタを含んでいてもよい。赤外線遮蔽フィルタの具体例としては、例えば、国際公開第２０１６／１８６０５０号、国際公開第２０１６／０３５６９５号、特許第６２４８９４５号公報、国際公開第２０１９／０２１７６７号、特開２０１７－０６７９６３号公報、特許第６５０６５２９号公報に記載されたフィルタが挙げられる。 The image sensor of the present invention may include an infrared shielding filter for the purpose of improving various performances such as noise reduction. Specific examples of the infrared shielding filter include, for example, International Publication No. 2016/186050, International Publication No. 2016/035695, Japanese Patent No. 6248945, International Publication No. 2019/021767, Japanese Patent Application Laid-Open No. 2017-06793, Patent. Examples thereof include the filters described in Japanese Patent Application Laid-Open No. 6506529.
　本発明のイメージセンサは誘電体多層膜を含んでいてもよい。誘電体多層膜としては、高屈折率の誘電体薄膜（高屈折率材料層）と低屈折率の誘電体薄膜（低屈折率材料層）とを交互に複数層積層したものが挙げられる。誘電体多層膜における誘電体薄膜の積層数は、特に限定はないが、２～１００層が好ましく、４～６０層がより好ましく、６～４０層が更に好ましい。高屈折率材料層の形成に用いられる材料としては、屈折率が１．７～２．５の材料が好ましい。具体例としては、Ｓｂ２Ｏ３、Ｓｂ２Ｓ３、Ｂｉ２Ｏ３、ＣｅＯ２、ＣｅＦ３、ＨｆＯ２、Ｌａ２Ｏ３、Ｎｄ２Ｏ３、Ｐｒ６Ｏ１１、Ｓｃ２Ｏ３、ＳｉＯ、Ｔａ２Ｏ５、ＴｉＯ２、ＴｌＣｌ、Ｙ２Ｏ３、ＺｎＳｅ、ＺｎＳ、ＺｒＯ２などが挙げられる。低屈折率材料層の形成に用いられる材料としては、屈折率が１．２～１．６の材料が好ましい。具体例としては、Ａｌ２Ｏ３、ＢｉＦ３、ＣａＦ２、ＬａＦ３、ＰｂＣｌ２、ＰｂＦ２、ＬｉＦ、ＭｇＦ２、ＭｇＯ、ＮｄＦ３、ＳｉＯ２、Ｓｉ２Ｏ３、ＮａＦ、ＴｈＯ２、ＴｈＦ４、Ｎａ３ＡｌＦ６などが挙げられる。誘電体多層膜の形成方法としては、特に制限はないが、例えば、イオンプレーティング、イオンビーム等の真空蒸着法、スパッタリング等の物理的気相成長法（ＰＶＤ法）、化学的気相成長法（ＣＶＤ法）などが挙げられる。高屈折率材料層および低屈折率材料層の各層の厚みは、遮断しようとする光の波長がλ（ｎｍ）であるとき、０．１λ～０．５λの厚みであることが好ましい。誘電体多層膜の具体例としては、例えば、特開２０１４－１３０３４４号公報、特開２０１８－０１０２９６号公報に記載の誘電体多層膜が挙げられる。 The image sensor of the present invention may include a dielectric multilayer film. Examples of the dielectric multilayer film include those in which a plurality of layers of a dielectric thin film having a high refractive index (high refractive index material layer) and a dielectric thin film having a low refractive index (low refractive index material layer) are alternately laminated. The number of laminated dielectric thin films in the dielectric multilayer film is not particularly limited, but is preferably 2 to 100 layers, more preferably 4 to 60 layers, and even more preferably 6 to 40 layers. As the material used for forming the high refractive index material layer, a material having a refractive index of 1.7 to 2.5 is preferable. Specific examples include Sb 2 O 3 , Sb 2 S 3 , Bi 2 O 3 , CeO 2 , CeF 3 , HfO 2 , La 2 O 3 , Nd 2 O 3 , Pr 6 O 11 , Sc 2 O 3 , SiO. , Ta 2 O 5 , TiO 2 , TlCl, Y 2 O 3 , ZnSe, ZnS, ZrO 2, and the like. As the material used for forming the low refractive index material layer, a material having a refractive index of 1.2 to 1.6 is preferable. Specific examples include Al 2 O 3 , BiF 3 , CaF 2 , LaF 3 , PbCl 2 , PbF 2 , LiF, MgF 2 , MgO, NdF 3 , SiO 2 , Si 2 O 3 , NaF, ThO 2 , ThF 4 , Na 3 AlF 6 and the like. The method for forming the dielectric multilayer film is not particularly limited, and for example, an ion plating method, a vacuum deposition method such as an ion beam, a physical vapor deposition method (PVD method) such as sputtering, or a chemical vapor deposition method. (CVD method) and the like. The thickness of each of the high refractive index material layer and the low refractive index material layer is preferably 0.1λ to 0.5λ when the wavelength of the light to be blocked is λ (nm). Specific examples of the dielectric multilayer film include the dielectric multilayer films described in JP-A-2014-130344 and JP-A-2018-010296.
　誘電体多層膜は、赤外域（好ましくは波長７００ｎｍを超える波長領域、より好ましくは波長８００ｎｍを超える波長領域、さらに好ましくは波長９００ｎｍを超える波長領域）に透過波長帯域が存在することが好ましい。透過波長帯域における最大透過率は７０％以上であることが好ましく、８０％以上であることがより好ましく、９０％以上であることが更に好ましい。また、遮光波長帯域における最大透過率は２０％以下であることが好ましく、１０％以下であることがより好ましく、５％以下であることが更に好ましい。また、透過波長帯域における平均透過率は６０％以上であることが好ましく、７０％以上であることがより好ましく、８０％以上であることが更に好ましい。また、透過波長帯域の波長範囲は、最大透過率を示す波長を中心波長λｔ１とした場合、中心波長λｔ１±１００ｎｍであることが好ましく、中心波長λｔ１±７５ｎｍであることがより好ましく、中心波長λｔ１±５０ｎｍであることが更に好ましい。 The dielectric multilayer film preferably has a transmission wavelength band in the infrared region (preferably a wavelength region having a wavelength of more than 700 nm, more preferably a wavelength region having a wavelength of more than 800 nm, and further preferably a wavelength region having a wavelength of more than 900 nm). The maximum transmittance in the transmission wavelength band is preferably 70% or more, more preferably 80% or more, and further preferably 90% or more. Further, the maximum transmittance in the light-shielding wavelength band is preferably 20% or less, more preferably 10% or less, and further preferably 5% or less. Further, the average transmittance in the transmission wavelength band is preferably 60% or more, more preferably 70% or more, and further preferably 80% or more. The wavelength range of the transmission wavelength band, when the center wavelength lambda t1 wavelengths showing a maximum transmittance is preferably the central wavelength lambda t1 ± 100 nm, more preferably the central wavelength lambda t1 ± 75 nm, It is more preferable that the center wavelength is λ t1 ± 50 nm.
　誘電体多層膜は、透過波長帯域（好ましくは、最大透過率が９０％以上の透過波長帯域）を１つのみ有していてもよく、複数有していてもよい。 The dielectric multilayer film may have only one transmission wavelength band (preferably, a transmission wavelength band having a maximum transmittance of 90% or more), or may have a plurality of transmission wavelength bands.
　本発明のイメージセンサは、色分離フィルタ層を含んでいてもよい。色分離フィルタ層としては着色画素を含むフィルタ層が挙げられる。着色画素の種類としては、赤色画素、緑色画素、青色画素、黄色画素、シアン色画素およびマゼンタ色画素などが挙げられる。色分離フィルタ層は２色以上の着色画素を含んでいてもよく、１色のみであってもよい。用途や目的に応じて適宜選択することができる。色分離フィルタ層は、例えば、国際公開第２０１９／０３９１７２号に記載のフィルタを用いることができる。 The image sensor of the present invention may include a color separation filter layer. Examples of the color separation filter layer include a filter layer including colored pixels. Examples of the types of colored pixels include red pixels, green pixels, blue pixels, yellow pixels, cyan pixels, magenta pixels, and the like. The color separation filter layer may include two or more colored pixels, or may have only one color. It can be appropriately selected according to the application and purpose. As the color separation filter layer, for example, the filter described in International Publication No. 2019/039172 can be used.
　また、色分離層が２色以上の着色画素を含む場合、各色の着色画素同士は隣接していてもよく、各着色画素間に隔壁が設けられていてもよい。隔壁の材質としては、特に限定はない。例えば、シロキサン樹脂、フッ素樹脂などの有機材料や、シリカ粒子などの無機粒子が挙げられる。また、隔壁は、タングステン、アルミニウムなどの金属で構成されていてもよい。 Further, when the color separation layer includes colored pixels of two or more colors, the colored pixels of each color may be adjacent to each other, and a partition wall may be provided between the colored pixels. The material of the partition wall is not particularly limited. Examples thereof include organic materials such as siloxane resin and fluororesin, and inorganic particles such as silica particles. Further, the partition wall may be made of a metal such as tungsten or aluminum.
　なお、本発明のイメージセンサが赤外線透過フィルタ層と色分離層とを含む場合は、色分離層は赤外線透過フィルタ層とは別の光路上に設けられていることが好ましい。また、赤外線透過フィルタ層と色分離層は二次元配置されていることも好ましい。なお、赤外線透過フィルタ層と色分離層とが二次元配置されているとは、両者の少なくとも一部が同一平面上に存在していることを意味する。 When the image sensor of the present invention includes an infrared transmission filter layer and a color separation layer, it is preferable that the color separation layer is provided on an optical path different from the infrared transmission filter layer. It is also preferable that the infrared transmission filter layer and the color separation layer are arranged two-dimensionally. The fact that the infrared transmission filter layer and the color separation layer are arranged two-dimensionally means that at least a part of both is present on the same plane.
　本発明のイメージセンサは、平坦化層、下地層、密着層などの中間層、反射防止膜、レンズを含んでいてもよい。反射防止膜としては、例えば、国際公開第２０１９／０１７２８０号に記載の組成物から作製した膜を用いることができる。レンズとしては、例えば、国際公開第２０１８／０９２６００号に記載の構造体を用いることができる。 The image sensor of the present invention may include an intermediate layer such as a flattening layer, a base layer, and an adhesion layer, an antireflection film, and a lens. As the antireflection film, for example, a film prepared from the composition described in International Publication No. 2019/017280 can be used. As the lens, for example, the structure described in International Publication No. 2018/092600 can be used.
　本発明の光検出素子は、赤外域の波長の光に対しても優れた感度を有している。このため、本発明のイメージセンサは、赤外線イメージセンサとして好ましく用いることができる。また、本発明のイメージセンサは、波長９００～２０００ｎｍの光をセンシングするものとして好ましく用いることができ、長９００～１６００ｎｍの光をセンシングするものとしてより好ましく用いることができる。 The photodetector of the present invention also has excellent sensitivity to light having a wavelength in the infrared region. Therefore, the image sensor of the present invention can be preferably used as an infrared image sensor. Further, the image sensor of the present invention can be preferably used for sensing light having a wavelength of 900 to 2000 nm, and more preferably for sensing light having a length of 900 to 1600 nm.
＜分散液＞
　本発明の分散液は、Ｓ原子１モルに対してＰｂ原子を１．７５モル以上１．９５モル以下含むＰｂＳ量子ドットと、ＰｂＳ量子ドットに配位する配位子と、溶剤と、を含む。 <Dispersion>
The dispersion liquid of the present invention contains a PbS quantum dot containing 1.75 mol or more and 1.95 mol or less of a Pb atom with respect to 1 mol of an S atom, a ligand coordinating the PbS quantum dot, and a solvent. ..
　分散液に用いられるＰｂＳ量子ドットについては光検出素子の項で説明したＰｂＳ量子ドットと同義である。分散液中のＰｂＳ量子ドットの含有量は、１～５００ｍｇ／ｍＬであることが好ましく、１０～２００ｍｇ／ｍＬであることがより好ましく、２０～１００ｍｇ／ｍＬであることが更に好ましい。 The PbS quantum dots used in the dispersion are synonymous with the PbS quantum dots described in the section on photodetectors. The content of PbS quantum dots in the dispersion is preferably 1 to 500 mg / mL, more preferably 10 to 200 mg / mL, and even more preferably 20 to 100 mg / mL.
　分散液に用いられる溶剤については、上述した分散液や配位子溶液に含まれる溶剤として説明したものが挙げられる。分散液中の溶剤の含有量は、分散液全質量に対し、５０～９９質量％であることが好ましく、７０～９９質量％であることがより好ましく、９０～９８質量％であることが更に好ましい。 Examples of the solvent used in the dispersion liquid include those described as the solvent contained in the dispersion liquid and the ligand solution described above. The content of the solvent in the dispersion is preferably 50 to 99% by mass, more preferably 70 to 99% by mass, and further preferably 90 to 98% by mass with respect to the total mass of the dispersion. preferable.
　分散液に含まれる配位子は、ＰｂＳ量子ドットに配位する配位子として働くと共に、立体障害となり易い分子構造を有しており、溶剤中にＰｂＳ量子ドットを分散させる分散剤としての役割も果たすものが好ましい。上記配位子は、ＰｂＳ量子ドットの分散性を向上する観点から、主鎖の炭素数が少なくとも６以上の配位子であることが好ましく、主鎖の炭素数が１０以上の配位子であることがより好ましい。配位子は、飽和化合物でも、不飽和化合物のいずれでもよい。配位子の具体例としては、デカン酸、ラウリン酸、ミリスチン酸、パルミチン酸、ステアリン酸、ベヘン酸、オレイン酸、エルカ酸、オレイルアミン、ドデシルアミン、ドデカンチオール、１，２－ヘキサデカンチオール、トリオクチルホスフィンオキシド、臭化セトリモニウム等が挙げられる。配位子は、半導体膜形成後に、膜中に残存し難いものが好ましい。具体的には、分子量が小さいことが好ましい。配位子は、ＰｂＳ量子ドットに分散安定性を持たせつつ、半導体膜に残存し難いという観点から、オレイン酸およびオレイルアミンが好ましい。また、分散液に含まれる配位子は、光検出素子の項で説明したハロゲン原子を含む配位子、および、配位部を２以上含む多座配位子などであってもよい。分散液中の配位子の含有量は、分散液の全体積に対し、０．１ｍｍｏｌ／Ｌ～２００ｍｍｏｌ／Ｌであることが好ましく、０．５ｍｍｏｌ／Ｌ～１０ｍｍｏｌ／Ｌであることがより好ましい。 The ligand contained in the dispersion liquid acts as a ligand for coordinating PbS quantum dots and has a molecular structure that easily causes steric hindrance, and serves as a dispersant for dispersing PbS quantum dots in a solvent. It is preferable that it also fulfills. From the viewpoint of improving the dispersibility of PbS quantum dots, the ligand is preferably a ligand having at least 6 or more carbon atoms in the main chain, and is a ligand having 10 or more carbon atoms in the main chain. More preferably. The ligand may be either a saturated compound or an unsaturated compound. Specific examples of the ligand include decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, erucic acid, oleylamine, dodecylamine, dodecanethiol, 1,2-hexadecanethiol, and trioctyl. Examples thereof include phosphine oxide and cetrimonium bromide. The ligand is preferably one that does not easily remain in the film after the formation of the semiconductor film. Specifically, it is preferable that the molecular weight is small. The ligands are preferably oleic acid and oleylamine from the viewpoint that the PbS quantum dots have dispersion stability and are unlikely to remain on the semiconductor film. Further, the ligand contained in the dispersion liquid may be a ligand containing a halogen atom described in the section of the photodetector, a multidentate ligand containing two or more coordination portions, or the like. The content of the ligand in the dispersion is preferably 0.1 mmol / L to 200 mmol / L, more preferably 0.5 mmol / L to 10 mmol / L, based on the total volume of the dispersion. ..
＜半導体膜＞
　本発明の半導体膜は、ＰｂＳ量子ドットの集合体と、ＰｂＳ量子ドットに配位する配位子と、を含む半導体膜であって、ＰｂＳ量子ドットは、Ｓ原子１モルに対してＰｂ原子を１．７５モル以上１．９５モル以下含む、半導体膜である。ＰｂＳ量子ドットは、Ｓ原子１モルに対してＰｂ原子を１．７５モル以上１．９０モル以下含むことが好ましい。ＰｂＳ量子ドットについては光検出素子の項で説明したＰｂＳ量子ドットと同義である。ＰｂＳ量子ドットに配位する配位子としては、光検出素子の項で説明したハロゲン原子を含む配位子、および、配位部を２以上含む多座配位子などが挙げられ、好ましい範も同様である。本発明の半導体膜は、光検出素子の光電変換層などに好ましく用いられる。 <Semiconductor film>
The semiconductor film of the present invention is a semiconductor film containing an aggregate of PbS quantum dots and a ligand that coordinates the PbS quantum dots, and the PbS quantum dots have Pb atoms for 1 mol of S atoms. A semiconductor film containing 1.75 mol or more and 1.95 mol or less. The PbS quantum dot preferably contains 1.75 mol or more and 1.90 mol or less of Pb atom with respect to 1 mol of S atom. The PbS quantum dot has the same meaning as the PbS quantum dot described in the section of the photodetector. Examples of the ligand that coordinates the PbS quantum dot include a ligand containing a halogen atom described in the section of the photodetector, and a polydentate ligand containing two or more coordination portions, which are preferable examples. Is the same. The semiconductor film of the present invention is preferably used for a photoelectric conversion layer of a photodetection element or the like.
　以下に実施例を挙げて本発明をさらに具体的に説明する。以下の実施例に示す材料、使用量、割合、処理内容、処理手順等は、本発明の趣旨を逸脱しない限り、適宜、変更することができる。従って、本発明の範囲は以下に示す具体例に限定されるものではない。 The present invention will be described in more detail with reference to examples below. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.
［ＰｂＳ量子ドットのＰｂ／Ｓ比（モル比）の評価方法］
　ＰｂＳ量子ドットの分散液を６０ｍｇ／ｍＬに濃縮した後、５０μＬ採取し、硝酸５ｍＬを添加後、マイクロウェーブで２３０℃に加熱して試料を分解した。そこに水を加えて全量を４０ｍＬとした後、誘導結合プラズマ（ＩＣＰ）発光分光分析装置（パーキンエルマー製Ｏｐｔｉｍａ７３００ＤＶ）を用いてＰｂＳ量子ドット中のＰｂ原子およびＳ原子をそれぞれ定量し、ＰｂＳ量子ドットのＰｂ／Ｓ比（モル比）を算出した。 [Evaluation method of Pb / S ratio (molar ratio) of PbS quantum dots]
The dispersion of PbS quantum dots was concentrated to 60 mg / mL, 50 μL was collected, 5 mL of nitric acid was added, and the sample was decomposed by heating to 230 ° C. with a microwave. After adding water to make the total volume 40 mL, Pb atoms and S atoms in the PbS quantum dots are quantified using an inductively coupled plasma (ICP) emission spectrophotometer (Optima 7300DV manufactured by PerkinElmer), and the PbS quantum dots are quantified. Pb / S ratio (molar ratio) was calculated.
（実施例１）
　フラスコ中に１．２８ｍＬのオレイン酸と、２ｍｍｏｌの酸化鉛と、３８ｍＬのオクタデセンを測りとり、真空下１１０℃で９０分加熱することで、前駆体溶液を得た。その後、溶液の温度を９５℃に調整し、系を窒素フロー状態にし、次いで、１ｍｍｏｌのヘキサメチルジシラチアンを５ｍＬのオクタデセンと共に注入した。注入後すぐにフラスコを自然冷却し、３０℃になった段階でヘキサン１２ｍＬを加え、溶液を回収した。溶液に過剰量のエタノールを加え、１００００ｒｐｍで１０分間遠心分離を行い、沈殿物をオクタンに分散させ、ＰｂＳ量子ドットの表面にオレイン酸が配位子として配位したＰｂＳ量子ドットの分散液（濃度１０ｍｇ／ｍＬ）を得た。得られたＰｂＳ量子ドットの分散液について、紫外可視近赤外分光光度計（日本分光（株）製、Ｖ－６７０）を用いた可視～赤外領域の光吸収測定から見積もったＰｂＳ量子ドットのバンドギャップはおよそ１．３２ｅＶであった。また、ＰｂＳ量子ドットのＰｂ／Ｓ比（モル比）を上記手法で算出したところ、ＰｂＳ量子ドットのＰｂ／Ｓ比（モル比）は１．９０であった。 (Example 1)
1.28 mL of oleic acid, 2 mmol of lead oxide and 38 mL of octadecene were measured in a flask and heated at 110 ° C. under vacuum for 90 minutes to obtain a precursor solution. The temperature of the solution was then adjusted to 95 ° C., the system was placed in a nitrogen flow state, and then 1 mmol of hexamethyldisiratene was injected with 5 mL of octadecene. Immediately after the injection, the flask was naturally cooled, and when the temperature reached 30 ° C., 12 mL of hexane was added and the solution was recovered. An excess amount of ethanol is added to the solution, and the mixture is centrifuged at 10000 rpm for 10 minutes to disperse the precipitate in octane, and the dispersion liquid (concentration) of PbS quantum dots in which oleic acid is coordinated as a ligand on the surface of the PbS quantum dots. 10 mg / mL) was obtained. The obtained dispersion of PbS quantum dots was estimated from light absorption measurements in the visible to infrared region using an ultraviolet-visible near-infrared spectrophotometer (V-670, manufactured by JASCO Corporation). The band gap was approximately 1.32 eV. Further, when the Pb / S ratio (molar ratio) of the PbS quantum dots was calculated by the above method, the Pb / S ratio (molar ratio) of the PbS quantum dots was 1.90.
　得られたＰｂＳ量子ドットの分散液を用いて以下の手法でフォトダイオード型の光検出素子を作製した。 Using the obtained dispersion of PbS quantum dots, a photodiode-type photodetector was manufactured by the following method.
　まず、フッ素ドープ酸化錫膜付き石英ガラス基板上に酸化チタン膜を５０ｎｍスパッタリングで成膜した。次に、ＰｂＳ量子ドットの分散液を上記基板に成膜した酸化チタン膜上に滴下し、２５００ｒｐｍでスピンコートして、ＰｂＳ量子ドット集合体膜を形成した（工程１）。次いで、このＰｂＳ量子ドット集合体膜上に、配位子溶液として、３－メルカプトプロピオン酸のメタノール溶液（濃度０．１ｍｏｌ／Ｌ）を滴下した後、１分間静置し、２５００ｒｐｍでスピンドライを行った。次いで、メタノールをＰｂＳ量子ドット集合体膜上に滴下し、２５００ｒｐｍで２０秒間スピンドライを行うことで、ＰｂＳ量子ドットに配位している配位子を、オレイン酸から３－メルカプトプロピオン酸に配位子交換した（工程２）。工程１と工程２とを１サイクルとする操作を３０サイクル繰り返し、配位子がオレイン酸から３－メルカプトプロピオン酸に配位子交換されたＰｂＳ量子ドット集合体膜である光電変換層を１００ｎｍの厚さで形成した。次に、光電変換層上に、酸化モリブデンを５０ｎｍ、金を１００ｎｍの厚さで連続蒸着により形成し、フォトダイオード型の光検出素子を得た。 First, a titanium oxide film was formed by 50 nm sputtering on a quartz glass substrate with a fluorine-doped tin oxide film. Next, the dispersion liquid of PbS quantum dots was dropped onto the titanium oxide film formed on the substrate and spin-coated at 2500 rpm to form a PbS quantum dot aggregate film (step 1). Next, a methanol solution of 3-mercaptopropionic acid (concentration 0.1 mol / L) was added dropwise onto the PbS quantum dot aggregate film as a ligand solution, and the mixture was allowed to stand for 1 minute and spin-dried at 2500 rpm. went. Next, methanol was dropped onto the PbS quantum dot aggregate membrane and spin-dried at 2500 rpm for 20 seconds to disperse the ligand coordinated to the PbS quantum dots from oleic acid to 3-mercaptopropionic acid. The position was exchanged (step 2). The operation of step 1 and step 2 as one cycle was repeated for 30 cycles, and the photoelectric conversion layer, which is a PbS quantum dot aggregate film in which the ligand was exchanged from oleic acid to 3-mercaptopropionic acid, was formed at 100 nm. Formed by thickness. Next, molybdenum oxide was formed on the photoelectric conversion layer with a thickness of 50 nm and gold was formed by continuous vapor deposition to obtain a photodiode-type photodetector.
（実施例２）
　ヘキサメチルジシラチアンを２．０ｍｍｏｌにかえた以外は実施例１と同様にしてＰｂＳ量子ドットの分散液を得た。ＰｂＳ量子ドットのバンドギャップはおよそ１．３２ｅＶであった。また、ＰｂＳ量子ドットのＰｂ／Ｓ比（モル比）は１．８１であった。 (Example 2)
A dispersion of PbS quantum dots was obtained in the same manner as in Example 1 except that hexamethyldisirateian was changed to 2.0 mmol. The bandgap of the PbS quantum dots was approximately 1.32 eV. The Pb / S ratio (molar ratio) of the PbS quantum dots was 1.81.
（実施例３）
　フラスコ中に、６．７４ｍＬのオレイン酸と、６．３ｍｍｏｌの酸化鉛と、３０ｍＬのオクタデセンを測りとり、真空下１２０℃で１００分加熱することで、前駆体溶液を得た。その後、溶液の温度を１００℃に調整し、系を窒素フロー状態にし、次いで、２．６ｍｍｏｌのヘキサメチルジシラチアンを５ｍＬのオクタデセンと共に注入した。注入後１分保持した後、フラスコを自然冷却し、３０℃になった段階でトルエン４０ｍＬを加え、溶液を回収した。溶液に過剰量のエタノールを加え、１００００ｒｐｍで１０分間遠心分離を行い、沈殿物をオクタンに分散させ、ＰｂＳ量子ドットの表面にオレイン酸が配位子として配位したＰｂＳ量子ドットの分散液（濃度１０ｍｇ／ｍＬ）を得た。得られたＰｂＳ量子ドットの分散液の吸収測定から見積もったＰｂＳ量子ドットのバンドギャップはおよそ１．３２ｅＶであった。また、ＰｂＳ量子ドットのＰｂ／Ｓ比（モル比）を上記手法で算出したところ、ＰｂＳ量子ドットのＰｂ／Ｓ比（モル比）は１．７５であった。このＰｂＳ量子ドットの分散液を用いて実施例１と同様の手法でフォトダイオード型の光検出素子を作製した。 (Example 3)
A precursor solution was obtained by measuring 6.74 mL of oleic acid, 6.3 mmol of lead oxide and 30 mL of octadecene in a flask and heating at 120 ° C. under vacuum for 100 minutes. The temperature of the solution was then adjusted to 100 ° C., the system was placed in a nitrogen flow state, and then 2.6 mmol of hexamethyldisiratene was injected with 5 mL of octadecene. After holding for 1 minute after injection, the flask was naturally cooled, 40 mL of toluene was added when the temperature reached 30 ° C., and the solution was recovered. An excess amount of ethanol is added to the solution, and the mixture is centrifuged at 10000 rpm for 10 minutes to disperse the precipitate in octane, and the dispersion liquid (concentration) of PbS quantum dots in which oleic acid is coordinated as a ligand on the surface of the PbS quantum dots. 10 mg / mL) was obtained. The band gap of the PbS quantum dots estimated from the absorption measurement of the dispersion liquid of the obtained PbS quantum dots was about 1.32 eV. Further, when the Pb / S ratio (molar ratio) of the PbS quantum dots was calculated by the above method, the Pb / S ratio (molar ratio) of the PbS quantum dots was 1.75. Using this PbS quantum dot dispersion, a photodiode-type photodetector was produced in the same manner as in Example 1.
（実施例４）
　配位子溶液として、３－メルカプトプロピオン酸のメタノール溶液（濃度０．１ｍｏｌ／Ｌ）の代わりに、ヨウ化亜鉛のメタノール溶液（濃度０．０２５ｍｏｌ／Ｌ）を用いた以外は実施例１と同様の手法で光検出素子を作製した。 (Example 4)
Same as Example 1 except that a methanol solution of zinc iodide (concentration 0.025 mol / L) was used instead of a methanol solution of 3-mercaptopropionic acid (concentration 0.1 mol / L) as the ligand solution. A light detection element was manufactured by the above method.
（実施例５）
　配位子溶液として、３－メルカプトプロピオン酸のメタノール溶液（濃度０．１ｍｏｌ／Ｌ）の代わりに、臭化亜鉛のメタノール溶液（濃度０．０２５ｍｏｌ／Ｌ）を用いた以外は実施例１と同様の手法で光検出素子を作製した。 (Example 5)
Same as Example 1 except that a methanol solution of zinc bromide (concentration 0.025 mol / L) was used instead of the methanol solution of 3-mercaptopropionic acid (concentration 0.1 mol / L) as the ligand solution. A light detection element was manufactured by the above method.
（実施例６）
　配位子溶液として、３－メルカプトプロピオン酸のメタノール溶液（濃度０．１ｍｏｌ／Ｌ）の代わりに、ヨウ化インジウムのメタノール溶液（濃度０．０２５ｍｏｌ／Ｌ）を用いた以外は実施例１と同様の手法で光検出素子を作製した。 (Example 6)
Same as Example 1 except that a methanol solution of indium iodide (concentration 0.025 mol / L) was used instead of the methanol solution of 3-mercaptopropionic acid (concentration 0.1 mol / L) as the ligand solution. A light detection element was manufactured by the above method.
（実施例７）
　配位子溶液として、３－メルカプトプロピオン酸とヨウ化亜鉛を含むメタノール溶液（３－メルカプトプロピオン酸濃度０．０１ｍｏｌ／Ｌ、ヨウ化亜鉛濃度０．０２５ｍｏｌ／Ｌ）を用いた以外は実施例１と同様の手法で光検出素子を作製した。 (Example 7)
Example 1 except that a methanol solution containing 3-mercaptopropionic acid and zinc iodide (3-mercaptopropionic acid concentration 0.01 mol / L, zinc iodide concentration 0.025 mol / L) was used as the ligand solution. A photodetector was produced in the same manner as in.
（実施例８～１１）
　Ｐｂ／Ｓ比（モル比）が１．９０であるＰｂＳ量子ドットを、実施例３に記載のＰｂ／Ｓ比（モル比）が１．７５であるＰｂＳ量子ドットに変更した以外は実施例４～７と同様の手法で光検出素子を作製した。 (Examples 8 to 11)
Example 4 except that the PbS quantum dots having a Pb / S ratio (molar ratio) of 1.90 were changed to the PbS quantum dots having a Pb / S ratio (molar ratio) of 1.75 described in Example 3. A photodetector was produced in the same manner as in 7 to 7.
（比較例１）
　ＰｂＳ量子ドットの分散液として、市販のＰｂＳ量子ドットの分散液（Ｓｉｇｍａ　Ａｌｄｒｉｃｈ社製、製品番号９００７３５）を用いた。ＰｂＳ量子ドットの分散液の吸収測定から見積もったバンドギャップはおよそ１．３２ｅＶであった。また、ＰｂＳ量子ドットのＰｂ／Ｓ比（モル比）を上記手法で算出したところ、ＰｂＳ量子ドットのＰｂ／Ｓ比（モル比）は１．６であった。このＰｂＳ量子ドットの分散液を用い、実施例１と同様の手法で光検出素子を作製した。 (Comparative Example 1)
As the dispersion liquid of PbS quantum dots, a commercially available dispersion liquid of PbS quantum dots (manufactured by Sigma-Aldrich, product number 900735) was used. The bandgap estimated from the absorption measurement of the dispersion of PbS quantum dots was about 1.32 eV. Further, when the Pb / S ratio (molar ratio) of the PbS quantum dots was calculated by the above method, the Pb / S ratio (molar ratio) of the PbS quantum dots was 1.6. Using this dispersion of PbS quantum dots, a photodetector was produced in the same manner as in Example 1.
（比較例２）
　フラスコ中に１．２８ｍＬのオレイン酸と、２ｍｍｏｌの酸化鉛と、３８ｍＬのオクタデセンを測りとり、真空下１１０℃で９０分加熱することで、前駆体溶液を得た。その後、溶液の温度を９５℃に調整し、系を窒素フロー状態にし、次いで、３．１ｍｍｏｌのヘキサメチルジシラチアンを５ｍＬのオクタデセンと共に注入した。注入後すぐにフラスコを自然冷却し、３０℃になった段階でヘキサン１２ｍＬを加え、溶液を回収した。溶液に過剰量のエタノールを加え、１００００ｒｐｍで１０分間遠心分離を行い、沈殿物をオクタンに分散させ、ＰｂＳ量子ドットの表面にオレイン酸が配位子として配位したＰｂＳ量子ドットの分散液（濃度１０ｍｇ／ｍＬ）を得た。得られたＰｂＳ量子ドットの分散液について、紫外可視近赤外分光光度計（日本分光（株）製、Ｖ－６７０）を用いた可視～赤外領域の光吸収測定から見積もったＰｂＳ量子ドットのバンドギャップはおよそ１．３２ｅＶであった。また、ＰｂＳ量子ドットのＰｂ／Ｓ比（モル比）を上記手法で算出したところ、ＰｂＳ量子ドットのＰｂ／Ｓ比（モル比）は１．７０であった。 (Comparative Example 2)
1.28 mL of oleic acid, 2 mmol of lead oxide and 38 mL of octadecene were measured in a flask and heated at 110 ° C. under vacuum for 90 minutes to obtain a precursor solution. The temperature of the solution was then adjusted to 95 ° C., the system was placed in a nitrogen flow state, and then 3.1 mmol of hexamethyldisiratene was injected with 5 mL of octadecene. Immediately after the injection, the flask was naturally cooled, and when the temperature reached 30 ° C., 12 mL of hexane was added and the solution was recovered. An excess amount of ethanol is added to the solution, and the mixture is centrifuged at 10000 rpm for 10 minutes to disperse the precipitate in octane, and the dispersion liquid (concentration) of PbS quantum dots in which oleic acid is coordinated as a ligand on the surface of the PbS quantum dots. 10 mg / mL) was obtained. The obtained dispersion of PbS quantum dots was estimated from light absorption measurements in the visible to infrared region using an ultraviolet-visible near-infrared spectrophotometer (V-670, manufactured by JASCO Corporation). The band gap was approximately 1.32 eV. Further, when the Pb / S ratio (molar ratio) of the PbS quantum dots was calculated by the above method, the Pb / S ratio (molar ratio) of the PbS quantum dots was 1.70.
＜評価＞
　各光検出素子について２Ｖの逆方向電圧を印加した状態で波長９４０ｎｍのモノクロ光（１００μＷ／ｃｍ２）を照射した際の外部量子効率を算出した。外部量子効率は光非照射時の電流値と光照射時の電流値の差分から見積もられる光電子数と、照射フォトン数から「外部量子効率＝（光電子数／照射フォトン数）×１００」で見積もった。
　併せて上記外部量子効率の算出を５０回繰り返した後の外部量子効率の変化度（１回目に測定した外部量子効率の値－５０回目に測定した外部量子効率の値）を算出して、繰り返し駆動に対する耐久性を評価した。外部量子効率の変化度の値が小さいほど繰り返し駆動に対する耐久性に優れていることを意味する。 <Evaluation>
The external quantum efficiency when irradiating monochrome light (100 μW / cm 2 ) with a wavelength of 940 nm with a reverse voltage of 2 V applied to each photodetector was calculated. The external quantum efficiency was estimated by "external quantum efficiency = (number of photoelectrons / number of irradiated photons) x 100" from the number of photoelectrons estimated from the difference between the current value when not irradiated with light and the current value when irradiated with light, and the number of irradiated photons. ..
At the same time, the degree of change in the external quantum efficiency after repeating the calculation of the external quantum efficiency 50 times (the value of the external quantum efficiency measured at the first time − the value of the external quantum efficiency measured at the 50th time) is calculated and repeated. The durability against driving was evaluated. The smaller the value of the degree of change in the external quantum efficiency, the better the durability against repeated driving.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　上記表に示すように、実施例の光検出素子は比較例よりも外部量子効率が高く、かつ、外部量子効率の変化度の値が小さく、繰り返し駆動に対する耐久性に優れていた。 As shown in the above table, the photodetector of the example had higher external quantum efficiency than the comparative example, the value of the degree of change of the external quantum efficiency was small, and the durability against repeated driving was excellent.
　上記実施例で得られた光検出素子を用い、国際公開第２０１６／１８６０５０号および国際公開第２０１６／１９０１６２号に記載の方法に従い作製した光学フィルタと共に公知の方法にてイメージセンサを作製し、固体撮像素子に組み込むことで、良好な可視、赤外撮像性能を有するイメージセンサを得ることができる。 Using the photodetector obtained in the above example, an image sensor was prepared by a known method together with an optical filter prepared according to the methods described in International Publication No. 2016/186050 and International Publication No. 2016/190162, and solidified. By incorporating it into an image sensor, an image sensor having good visible and infrared imaging performance can be obtained.
１：光検出素子
１１：上部電極
１２：下部電極
１３：光電変換層 1: Photodetection element 11: Upper electrode 12: Lower electrode 13: Photoelectric conversion layer

Claims (16)

  1. 　ＰｂＳ量子ドットの集合体と、前記ＰｂＳ量子ドットに配位する配位子と、を含む光電変換層を有する光検出素子であって、
    　前記ＰｂＳ量子ドットは、Ｓ原子１モルに対してＰｂ原子を１．７５モル以上１．９５モル以下含む、光検出素子。     A photodetector having a photoelectric conversion layer containing an aggregate of PbS quantum dots and a ligand coordinating the PbS quantum dots.
    The PbS quantum dot is a photodetector containing 1.75 mol or more and 1.95 mol or less of Pb atom with respect to 1 mol of S atom.
  2. 　前記ＰｂＳ量子ドットは、Ｓ原子１モルに対してＰｂ原子を１．７５モル以上１．９０モル以下含む、請求項１に記載の光検出素子。 The photodetector according to claim 1, wherein the PbS quantum dot contains 1.75 mol or more and 1.90 mol or less of Pb atom with respect to 1 mol of S atom.
  3. 　前記配位子は、ハロゲン原子を含む配位子、および、配位部を２以上含む多座配位子から選ばれる少なくとも１種を含む請求項１または２に記載の光検出素子。 The light detection element according to claim 1 or 2, wherein the ligand contains at least one selected from a ligand containing a halogen atom and a polydentate ligand containing two or more coordination portions.
  4. 　前記ハロゲン原子を含む配位子が無機ハロゲン化物である、請求項３に記載の光検出素子。 The photodetector according to claim 3, wherein the ligand containing the halogen atom is an inorganic halide.
  5. 　前記無機ハロゲン化物はＺｎ原子を含む、請求項４に記載の光検出素子。 The photodetector according to claim 4, wherein the inorganic halide contains a Zn atom.
  6. 　前記ハロゲン原子を含む配位子がヨウ素原子を含む、請求項３～５のいずれか１項に記載の光検出素子。 The photodetector according to any one of claims 3 to 5, wherein the ligand containing a halogen atom contains an iodine atom.
  7. 　前記配位子が、３－メルカプトプロピオン酸、ヨウ化亜鉛、臭化亜鉛およびヨウ化インジウムから選ばれる少なくとも１種を含む、請求項１～６のいずれか１項に記載の光検出素子。 The photodetector according to any one of claims 1 to 6, wherein the ligand contains at least one selected from 3-mercaptopropionic acid, zinc iodide, zinc bromide and indium iodide.
  8. 　前記配位子は、２種以上の配位子を含む、請求項１～７のいずれか１項に記載の光検出素子。 The photodetector according to any one of claims 1 to 7, wherein the ligand contains two or more kinds of ligands.
  9. 　前記配位子は、ハロゲン原子を含む配位子と、配位部を２以上含む多座配位子とを含む、請求項１～８のいずれか１項に記載の光検出素子。 The light detection element according to any one of claims 1 to 8, wherein the ligand includes a ligand containing a halogen atom and a polydentate ligand containing two or more coordination portions.
  10. 　フォトダイオード型の光検出素子である、請求項１～９のいずれか１項に記載の光検出素子。 The photodetector according to any one of claims 1 to 9, which is a photodiode type photodetector.
  11. 　請求項１～１０のいずれか１項に記載の光検出素子の製造方法であって、
    　Ｓ原子１モルに対してＰｂ原子を１．７５モル以上１．９５モル以下含むＰｂＳ量子ドットと、前記ＰｂＳ量子ドットに配位する配位子と、溶剤と、を含む分散液を用いて前記ＰｂＳ量子ドットの集合体の膜を形成する工程を含む、光検出素子の製造方法。     The method for manufacturing a photodetector according to any one of claims 1 to 10.
    The dispersion liquid containing a PbS quantum dot containing 1.75 mol or more and 1.95 mol or less of a Pb atom with respect to 1 mol of an S atom, a ligand coordinating to the PbS quantum dot, and a solvent was used. A method for manufacturing a photodetector, which comprises a step of forming a film of an aggregate of PbS quantum dots.
  12. 　請求項１～１０のいずれか１項に記載の光検出素子を含むイメージセンサ。 An image sensor including the photodetection element according to any one of claims 1 to 10.
  13. 　波長９００～１６００ｎｍの光をセンシングする、請求項１２に記載のイメージセンサ。 The image sensor according to claim 12, which senses light having a wavelength of 900 to 1600 nm.
  14. 　赤外線イメージセンサである、請求項１２に記載のイメージセンサ。 The image sensor according to claim 12, which is an infrared image sensor.
  15. 　Ｓ原子１モルに対してＰｂ原子を１．７５モル以上１．９５モル以下含むＰｂＳ量子ドットと、前記ＰｂＳ量子ドットに配位する配位子と、溶剤と、を含む分散液。 A dispersion containing a PbS quantum dot containing 1.75 mol or more and 1.95 mol or less of a Pb atom with respect to 1 mol of S atom, a ligand coordinating to the PbS quantum dot, and a solvent.
  16. 　ＰｂＳ量子ドットの集合体と、前記ＰｂＳ量子ドットに配位する配位子と、を含む半導体膜であって、
    　前記ＰｂＳ量子ドットは、Ｓ原子１モルに対して１．７５モル以上１．９５モル以下含む、半導体膜。     A semiconductor film containing an aggregate of PbS quantum dots and a ligand coordinating the PbS quantum dots.
    The PbS quantum dot is a semiconductor film containing 1.75 mol or more and 1.95 mol or less with respect to 1 mol of S atom.
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